title: My Liquid tag is not recognized by GitHub pages
body: <p>I used Jekyll 3.8.5 and built a blog on GitHub. I also used <a href="https://github.com/linjer/jekyll-katex" rel="nofollow noreferrer">Jekyll-Katex 0.3.0</a>, a Jekyll plugin for easy server-side math rendering via KaTeX. Everything works fine on my local machine. But when I pushed it to GitHub, I got this: "Your site is having problems building: The tag Katexmm on line 11 in _posts/2019-01-22-ECDSA-and-Bitcoin-I.md is not a recognized Liquid tag."</p>
  
  <p>"Katexmm" is a <a href="https://github.com/linjer/jekyll-katex#katexmm" rel="nofollow noreferrer">liquid tag of Jekyll-Katex</a>, so I checked dependencies. <a href="https://github.com/linjer/jekyll-katex/blob/master/jekyll-katex.gemspec" rel="nofollow noreferrer">Jekyll-Katex 0.3.0 requires Jekyll ~> 3.8</a> while <a href="https://pages.github.com/versions/" rel="nofollow noreferrer">GitHub Pages uses Jekyll 3.7.4</a>. I guess that's the problem.</p>
  
  <p>What shall I do? 
  One more thing: I want to use "katexmm", please don't suggest me to use Jekyll 3.7.4 instead of  3.8.5.
  Thanks in advance.</p>
  
  <p>I followed ashmaroli's suggestion, but still doesn't work. I tried Nelify and "Deploy failed":</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>11:31:01 AM: Build ready to start
  11:31:03 AM: build-image version: 84aca9ba39e0ee86ba194760fbfc51a808f62543
  11:31:04 AM: buildbot version: 57d44fd1631cc3fff8b38fbaf88d3d04f946418a
  11:31:04 AM: Fetching cached dependencies
  11:31:04 AM: Starting to download cache of 254.7KB
  11:31:04 AM: Finished downloading cache in 147.184771ms
  11:31:04 AM: Starting to extract cache
  11:31:04 AM: Failed to fetch cache, continuing with build
  11:31:04 AM: Starting to prepare the repo for build
  11:31:04 AM: No cached dependencies found. Cloning fresh repo
  11:31:04 AM: git clone https://github.com/Jun-Wang-2018/Blog
  11:31:05 AM: Preparing Git Reference refs/heads/gh-pages
  11:31:06 AM: Starting build script
  11:31:06 AM: Installing dependencies
  11:31:08 AM: Downloading and installing node v8.15.0...
  11:31:08 AM: Downloading https://nodejs.org/dist/v8.15.0/node-v8.15.0-linux-x64.tar.xz...
  11:31:08 AM:      0.0%
  11:31:08 AM: 
  ######
  11:31:08 AM:                    8.4%
  11:31:08 AM: 
  #############################################
  11:31:08 AM: ###                          66.8%
  11:31:08 AM: 
  ######################################
  11:31:08 AM: ################################## 100.0%
  11:31:08 AM: Computing checksum with sha256sum
  11:31:08 AM: Checksums matched!
  11:31:11 AM: Now using node v8.15.0 (npm v6.4.1)
  11:31:12 AM: Attempting ruby version 2.3.6, read from environment
  11:31:13 AM: Using ruby version 2.3.6
  11:31:15 AM: Using PHP version 5.6
  11:31:15 AM: Started restoring cached ruby gems
  11:31:15 AM: Finished restoring cached ruby gems
  11:31:15 AM: Installing gem bundle
  11:31:15 AM: You must use Bundler 2 or greater with this lockfile.
  11:31:15 AM: Error during gem install
  11:31:15 AM: Error running command: Build script returned non-zero exit code: 1
  11:31:15 AM: Failing build: Failed to build site
  11:31:15 AM: failed during stage 'building site': Build script returned non-zero exit code: 1
  11:31:15 AM: Finished processing build request in 11.629358799s</code></pre>
  </div>
  </div>
  </p>
  
  <p>I tried Cloudcannon and "Jekyll build failed":</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>Syncing raw files... done
  Checking existing local bundle state... failed
  Loading gem cache... 
  Checking gem cache (bundle_cache/A16MrNFnrU9wWPnsPr5G8PkR_kBFEHG0ytrPjGtZ7mQ.zip)... no cache
  
  $ export JEKYLL_ENV="production"
  
  $ ruby -v
  
  ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-linux]
  
  $ bundle -v
  
  Bundler version 1.16.6
  
  $ bundle config --global jobs 4
  
  Configured concurrent installs!
  
  $ bundle install
  
  Using local cacheable path...
  You must use Bundler 2 or greater with this lockfile.</code></pre>
  </div>
  </div>
  </p>