config: Remove unused github-metadata plugin

Author: gonX

site/Gemfile

@@ -12,9 +12,9 @@ source "https://rubygems.org"
 # If you want to use GitHub Pages, remove the "gem "jekyll"" above and
 # uncomment the line below. To upgrade, run `bundle update github-pages`.
 gem 'jekyll', '~> 4.3'
-# If you have any plugins, put them here!
+
 group :jekyll_plugins do
-  gem 'jekyll-github-metadata', '~> 2.16'
+  # If you have any plugins, put them here!
 end
 
 gem 'json'