title: Issues serving Jekyll to localhost, eventmachine 1.2.7 has an error when installing
body: <p>Not sure what to do to specifically fix this problem, googled and nothing solved my question.  When I try to:</p>
  <p><code>bundle exec jekyll serve</code></p>
  <p>I get told:</p>
  <pre><code>Could not find eventmachine-1.2.7 in any of the sources
  Run `bundle install` to install missing gems.
  
  </code></pre>
  <p>Then I:</p>
  <p><code>bundle install</code></p>
  <p>Only to get this:</p>
  <pre><code>Installing eventmachine 1.2.7 with native extensions
  Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
  
      current directory: /private/var/folders/7f/2c2swwc1153899dmr8781_x40000gn/T/bundler20201130-34411-1lzt2fceventmachine-1.2.7/gems/eventmachine-1.2.7/ext
  /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby -I /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0 -r
  ./siteconf20201130-34411-pd54nh.rb extconf.rb
  mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/include/ruby.h
  
  You might have to install separate package for the ruby development
  environment, ruby-dev or ruby-devel for example.
  
  extconf failed, exit code 1
  
  Gem files will remain installed in /var/folders/7f/2c2swwc1153899dmr8781_x40000gn/T/bundler20201130-34411-1lzt2fceventmachine-1.2.7/gems/eventmachine-1.2.7 for
  inspection.
  Results logged to
  /var/folders/7f/2c2swwc1153899dmr8781_x40000gn/T/bundler20201130-34411-1lzt2fceventmachine-1.2.7/extensions/universal-darwin-20/2.6.0/eventmachine-1.2.7/gem_make.out
  
  An error occurred while installing eventmachine (1.2.7), and Bundler cannot continue.
  Make sure that `gem install eventmachine -v '1.2.7' --source 'https://rubygems.org/'` succeeds before bundling.
  
  In Gemfile:
    minima was resolved to 2.5.1, which depends on
      jekyll-feed was resolved to 0.13.0, which depends on
        jekyll was resolved to 4.0.0, which depends on
          em-websocket was resolved to 0.5.1, which depends on
            eventmachine
  
  </code></pre>
  <p>Where am I going wrong here?  Just updated to macOS 11.0.1, this is my first time trying to serve jekyll since the update.  Thanks y'all!</p>