updated Gemfile to latest gem versions so it works with Ruby 3

Author: tclose

.gitignore

@@ -1,3 +1,5 @@
 _site
 .sass-cache
 .jekyll-metadata
+.DS_Store
+Gemfile.lock

Gemfile

@@ -9,17 +9,19 @@ ruby RUBY_VERSION
 #
 # This will help ensure the proper Jekyll version is running.
 # Happy Jekylling!
-gem "jekyll", "3.6.3"
+gem "jekyll", "3.9.4"
 
 # This is the default theme for new Jekyll sites. You may change this to anything you like.
-gem "minima", "~> 2.0"
+gem "minima", "~> 2.5.2"
+gem "kramdown-parser-gfm"
+gem "webrick"
 
 # 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 "github-pages", group: :jekyll_plugins
 
 # If you have any plugins, put them here!
 group :jekyll_plugins do
-  gem "jekyll-feed", "~> 0.6"
+  gem "jekyll-feed", "~> 0.17"
   gem 'jekyll-contentblocks'
 end