prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  Return secure URLs for the fields thumbnail, detail_url and related_url.
  _(Framed the verbiage of the title as a feature request)_ 🙏 
  
  ## Problem
  
  The response for search and detail requests includes insecure URLs (`http` instead of `https`) in the fields `thumbnail`, `detail_url` and `related_url`.
  
  ![image](https://user-images.githubusercontent.com/746152/158834288-6b49c399-3b8c-48c8-8529-cdff970686a3.png)
  
  
  e.g.:
  
  **Search**
  
  https://api.openverse.engineering/v1/images/?q=flower
  
  **Detail:**
  
  https://api.openverse.engineering/v1/images/6c1769b0-a3e5-4dae-8a36-8531a6e1430f/
  
  ## Description
  
  When trying to integrate Openverse with some code on the browser I ended up having to replace the scheme part of the URL for avoiding notices like ```xxxx was loaded over HTTPS, but requested an insecure resource 'http://api.openverse.engineering/v1/images/6c1769b0-a3e5-4dae-8a36-8531a6e1430f/'. This request has been blocked; the content must be served over HTTPS.`
   
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `api/catalog/api/serializers/base.py`
  Content:
  ```
  1 import re
  2 
  3 from django.conf import settings
  4 from rest_framework import serializers
  5 
  6 
  7 class SchemableHyperlinkedIdentityField(serializers.HyperlinkedIdentityField):
  8     """
  9     This field returns the link but allows the option to replace the URL scheme.
  10     """
  11 
  12     def __init__(self, scheme=settings.API_LINK_SCHEME, *args, **kwargs):
  13         super().__init__(*args, **kwargs)
  14 
  15         self.scheme = scheme
  16 
  17     def get_url(self, *args, **kwargs):
  18         url = super().get_url(*args, **kwargs)
  19 
  20         # Only rewrite URLs if a fixed scheme is provided
  21         if self.scheme is not None:
  22             re.sub(r"^\w+://", f"{self.scheme}://", url, 1)
  23 
  24         return url
  25
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/api/catalog/api/serializers/base.py b/api/catalog/api/serializers/base.py
  --- a/api/catalog/api/serializers/base.py
  +++ b/api/catalog/api/serializers/base.py
  @@ -19,6 +19,6 @@
   
           # Only rewrite URLs if a fixed scheme is provided
           if self.scheme is not None:
  -            re.sub(r"^\w+://", f"{self.scheme}://", url, 1)
  +            url = re.sub(r"^\w+://", f"{self.scheme}://", url, 1)
   
           return url
  
verification_info: {"golden_diff": "diff --git a/api/catalog/api/serializers/base.py b/api/catalog/api/serializers/base.py\n--- a/api/catalog/api/serializers/base.py\n+++ b/api/catalog/api/serializers/base.py\n@@ -19,6 +19,6 @@\n \n         # Only rewrite URLs if a fixed scheme is provided\n         if self.scheme is not None:\n-            re.sub(r\"^\\w+://\", f\"{self.scheme}://\", url, 1)\n+            url = re.sub(r\"^\\w+://\", f\"{self.scheme}://\", url, 1)\n \n         return url\n", "issue": "Return secure URLs for the fields thumbnail, detail_url and related_url.\n_(Framed the verbiage of the title as a feature request)_ \ud83d\ude4f \r\n\r\n## Problem\r\n\r\nThe response for search and detail requests includes insecure URLs (`http` instead of `https`) in the fields `thumbnail`, `detail_url` and `related_url`.\r\n\r\n![image](https://user-images.githubusercontent.com/746152/158834288-6b49c399-3b8c-48c8-8529-cdff970686a3.png)\r\n\r\n\r\ne.g.:\r\n\r\n**Search**\r\n\r\nhttps://api.openverse.engineering/v1/images/?q=flower\r\n\r\n**Detail:**\r\n\r\nhttps://api.openverse.engineering/v1/images/6c1769b0-a3e5-4dae-8a36-8531a6e1430f/\r\n\r\n## Description\r\n\r\nWhen trying to integrate Openverse with some code on the browser I ended up having to replace the scheme part of the URL for avoiding notices like ```xxxx was loaded over HTTPS, but requested an insecure resource 'http://api.openverse.engineering/v1/images/6c1769b0-a3e5-4dae-8a36-8531a6e1430f/'. This request has been blocked; the content must be served over HTTPS.`\r\n \r\n\n", "before_files": [{"content": "import re\n\nfrom django.conf import settings\nfrom rest_framework import serializers\n\n\nclass SchemableHyperlinkedIdentityField(serializers.HyperlinkedIdentityField):\n    \"\"\"\n    This field returns the link but allows the option to replace the URL scheme.\n    \"\"\"\n\n    def __init__(self, scheme=settings.API_LINK_SCHEME, *args, **kwargs):\n        super().__init__(*args, **kwargs)\n\n        self.scheme = scheme\n\n    def get_url(self, *args, **kwargs):\n        url = super().get_url(*args, **kwargs)\n\n        # Only rewrite URLs if a fixed scheme is provided\n        if self.scheme is not None:\n            re.sub(r\"^\\w+://\", f\"{self.scheme}://\", url, 1)\n\n        return url\n", "path": "api/catalog/api/serializers/base.py"}], "after_files": [{"content": "import re\n\nfrom django.conf import settings\nfrom rest_framework import serializers\n\n\nclass SchemableHyperlinkedIdentityField(serializers.HyperlinkedIdentityField):\n    \"\"\"\n    This field returns the link but allows the option to replace the URL scheme.\n    \"\"\"\n\n    def __init__(self, scheme=settings.API_LINK_SCHEME, *args, **kwargs):\n        super().__init__(*args, **kwargs)\n\n        self.scheme = scheme\n\n    def get_url(self, *args, **kwargs):\n        url = super().get_url(*args, **kwargs)\n\n        # Only rewrite URLs if a fixed scheme is provided\n        if self.scheme is not None:\n            url = re.sub(r\"^\\w+://\", f\"{self.scheme}://\", url, 1)\n\n        return url\n", "path": "api/catalog/api/serializers/base.py"}]}