We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Support httpcore>=0.16.0
Hi,

I have a project that uses `fastapi` and `uvicorn` which demands `h11>=0.8`. Latest version of `fastapi` changed their test suite from `requests` to `httpx`. So I had to add `httpx` to my tests requirements.

Now the problem is, that `httpx` requires `httpcore`, which since version `0.16.0` allows for `h11==0.14.0`, but the current version of `httpcore` required by `httpx` doesn't, so I end up having to downgrade the `h11==0.14.0` which I have to `0.12.0`.

Can the constraint for `httpcore` be updated to `>=0.16.0` here?

--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `setup.py`
Content:
```
1 import sys
2 
3 from setuptools import setup
4 
5 sys.stderr.write(
6     """
7 ===============================
8 Unsupported installation method
9 ===============================
10 httpx no longer supports installation with `python setup.py install`.
11 Please use `python -m pip install .` instead.
12 """
13 )
14 sys.exit(1)
15 
16 
17 # The below code will never execute, however GitHub is particularly
18 # picky about where it finds Python packaging metadata.
19 # See: https://github.com/github/feedback/discussions/6456
20 #
21 # To be removed once GitHub catches up.
22 
23 setup(
24     name="httpx",
25     install_requires=[
26         "certifi",
27         "sniffio",
28         "rfc3986[idna2008]>=1.3,<2",
29         "httpcore>=0.15.0,<0.16.0",
30     ],
31 )
32
```

Path: `httpx/__version__.py`
Content:
```
1 __title__ = "httpx"
2 __description__ = "A next generation HTTP client, for Python 3."
3 __version__ = "0.23.0"
4
```
--- 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()

```

diff --git a/httpx/__version__.py b/httpx/__version__.py
--- a/httpx/__version__.py
+++ b/httpx/__version__.py
@@ -1,3 +1,3 @@
 __title__ = "httpx"
 __description__ = "A next generation HTTP client, for Python 3."
-__version__ = "0.23.0"
+__version__ = "0.23.1"
diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -26,6 +26,6 @@
         "certifi",
         "sniffio",
         "rfc3986[idna2008]>=1.3,<2",
-        "httpcore>=0.15.0,<0.16.0",
+        "httpcore>=0.15.0,<0.17.0",
     ],
 )

{"golden_diff": "diff --git a/httpx/__version__.py b/httpx/__version__.py\n--- a/httpx/__version__.py\n+++ b/httpx/__version__.py\n@@ -1,3 +1,3 @@\n __title__ = \"httpx\"\n __description__ = \"A next generation HTTP client, for Python 3.\"\n-__version__ = \"0.23.0\"\n+__version__ = \"0.23.1\"\ndiff --git a/setup.py b/setup.py\n--- a/setup.py\n+++ b/setup.py\n@@ -26,6 +26,6 @@\n         \"certifi\",\n         \"sniffio\",\n         \"rfc3986[idna2008]>=1.3,<2\",\n-        \"httpcore>=0.15.0,<0.16.0\",\n+        \"httpcore>=0.15.0,<0.17.0\",\n     ],\n )\n", "issue": "Support httpcore>=0.16.0\nHi,\r\n\r\nI have a project that uses `fastapi` and `uvicorn` which demands `h11>=0.8`. Latest version of `fastapi` changed their test suite from `requests` to `httpx`. So I had to add `httpx` to my tests requirements.\r\n\r\nNow the problem is, that `httpx` requires `httpcore`, which since version `0.16.0` allows for `h11==0.14.0`, but the current version of `httpcore` required by `httpx` doesn't, so I end up having to downgrade the `h11==0.14.0` which I have to `0.12.0`.\r\n\r\nCan the constraint for `httpcore` be updated to `>=0.16.0` here?\n", "before_files": [{"content": "import sys\n\nfrom setuptools import setup\n\nsys.stderr.write(\n    \"\"\"\n===============================\nUnsupported installation method\n===============================\nhttpx no longer supports installation with `python setup.py install`.\nPlease use `python -m pip install .` instead.\n\"\"\"\n)\nsys.exit(1)\n\n\n# The below code will never execute, however GitHub is particularly\n# picky about where it finds Python packaging metadata.\n# See: https://github.com/github/feedback/discussions/6456\n#\n# To be removed once GitHub catches up.\n\nsetup(\n    name=\"httpx\",\n    install_requires=[\n        \"certifi\",\n        \"sniffio\",\n        \"rfc3986[idna2008]>=1.3,<2\",\n        \"httpcore>=0.15.0,<0.16.0\",\n    ],\n)\n", "path": "setup.py"}, {"content": "__title__ = \"httpx\"\n__description__ = \"A next generation HTTP client, for Python 3.\"\n__version__ = \"0.23.0\"\n", "path": "httpx/__version__.py"}], "after_files": [{"content": "import sys\n\nfrom setuptools import setup\n\nsys.stderr.write(\n    \"\"\"\n===============================\nUnsupported installation method\n===============================\nhttpx no longer supports installation with `python setup.py install`.\nPlease use `python -m pip install .` instead.\n\"\"\"\n)\nsys.exit(1)\n\n\n# The below code will never execute, however GitHub is particularly\n# picky about where it finds Python packaging metadata.\n# See: https://github.com/github/feedback/discussions/6456\n#\n# To be removed once GitHub catches up.\n\nsetup(\n    name=\"httpx\",\n    install_requires=[\n        \"certifi\",\n        \"sniffio\",\n        \"rfc3986[idna2008]>=1.3,<2\",\n        \"httpcore>=0.15.0,<0.17.0\",\n    ],\n)\n", "path": "setup.py"}, {"content": "__title__ = \"httpx\"\n__description__ = \"A next generation HTTP client, for Python 3.\"\n__version__ = \"0.23.1\"\n", "path": "httpx/__version__.py"}]}