revert: Gem updates

Require Ruby 2.7

Gemfile

@@ -11,5 +11,3 @@ group :jekyll_plugins do
    gem 'jekyll-multiple-languages-plugin'
    gem "jekyll-paginate"
 end
-
-gem "webrick", "~> 1.8"

Gemfile.lock

@@ -1,43 +1,34 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (7.1.2)
-      base64
-      bigdecimal
+    activesupport (6.0.3.4)
       concurrent-ruby (~> 1.0, >= 1.0.2)
-      connection_pool (>= 2.2.5)
-      drb
-      i18n (>= 1.6, < 2)
-      minitest (>= 5.1)
-      mutex_m
-      tzinfo (~> 2.0)
-    addressable (2.8.6)
-      public_suffix (>= 2.0.2, < 6.0)
-    base64 (0.2.0)
-    bigdecimal (3.1.5)
+      i18n (>= 0.7, < 2)
+      minitest (~> 5.1)
+      tzinfo (~> 1.1)
+      zeitwerk (~> 2.2, >= 2.2.2)
+    addressable (2.7.0)
+      public_suffix (>= 2.0.2, < 5.0)
     colorator (1.1.0)
-    concurrent-ruby (1.2.2)
-    connection_pool (2.4.1)
-    drb (2.2.0)
-      ruby2_keywords
-    em-websocket (0.5.3)
+    concurrent-ruby (1.1.7)
+    em-websocket (0.5.2)
       eventmachine (>= 0.12.9)
-      http_parser.rb (~> 0)
+      http_parser.rb (~> 0.6.0)
     eventmachine (1.2.7)
-    ffi (1.16.3)
+    ffi (1.13.1)
     forwardable-extended (2.6.0)
-    gemoji (4.1.0)
-    html-pipeline (2.14.3)
+    gemoji (3.0.1)
+    html-pipeline (2.14.0)
       activesupport (>= 2)
       nokogiri (>= 1.4)
-    http_parser.rb (0.8.0)
-    i18n (1.14.1)
+    http_parser.rb (0.6.0)
+    i18n (0.9.5)
       concurrent-ruby (~> 1.0)
-    jekyll (3.9.4)
+    jekyll (3.9.0)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
-      i18n (>= 0.7, < 2)
+      i18n (~> 0.7)
       jekyll-sass-converter (~> 1.0)
       jekyll-watch (~> 2.0)
       kramdown (>= 1.17, < 3)
@@ -46,59 +37,60 @@ GEM
       pathutil (~> 0.9)
       rouge (>= 1.7, < 4)
       safe_yaml (~> 1.0)
-    jekyll-multiple-languages-plugin (1.8.0)
+    jekyll-multiple-languages-plugin (1.7.0)
       jekyll (>= 2.0, < 5.0)
     jekyll-paginate (1.1.0)
     jekyll-sass-converter (1.5.2)
       sass (~> 3.4)
     jekyll-sitemap (1.4.0)
       jekyll (>= 3.7, < 5.0)
-    jekyll-toc (0.18.0)
-      jekyll (>= 3.9)
-      nokogiri (~> 1.12)
+    jekyll-toc (0.15.0)
+      jekyll (>= 3.8)
+      nokogiri (~> 1.10)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
-    jemoji (0.13.0)
-      gemoji (>= 3, < 5)
+    jemoji (0.12.0)
+      gemoji (~> 3.0)
       html-pipeline (~> 2.2)
       jekyll (>= 3.0, < 5.0)
-    kramdown (2.4.0)
+    kramdown (2.3.0)
       rexml
-    liquid (4.0.4)
-    listen (3.8.0)
+    liquid (4.0.3)
+    listen (3.2.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
-    mini_portile2 (2.8.5)
-    minitest (5.20.0)
-    mutex_m (0.2.0)
-    nokogiri (1.16.0)
-      mini_portile2 (~> 2.8.2)
+    mini_portile2 (2.8.2)
+    minitest (5.14.2)
+    multi_json (1.15.0)
+    nokogiri (1.13.10)
+      mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (5.0.4)
-    pygments.rb (2.4.1)
-    racc (1.7.3)
+    public_suffix (4.0.6)
+    pygments.rb (1.2.1)
+      multi_json (>= 1.0.0)
+    racc (1.6.2)
     rake (10.5.0)
     rake-jekyll (1.1.0)
       rake (~> 10.0)
-    rb-fsevent (0.11.2)
+    rb-fsevent (0.10.4)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    redcarpet (3.6.0)
-    rexml (3.2.6)
-    rouge (3.30.0)
-    ruby2_keywords (0.0.5)
+    redcarpet (3.5.0)
+    rexml (3.2.4)
+    rouge (3.24.0)
     safe_yaml (1.0.5)
     sass (3.7.4)
       sass-listen (~> 4.0.0)
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
-    tzinfo (2.0.6)
-      concurrent-ruby (~> 1.0)
-    webrick (1.8.1)
+    thread_safe (0.3.6)
+    tzinfo (1.2.7)
+      thread_safe (~> 0.1)
+    zeitwerk (2.4.1)
 
 PLATFORMS
   ruby
@@ -114,7 +106,6 @@ DEPENDENCIES
   rake
   rake-jekyll
   redcarpet
-  webrick (~> 1.8)
 
 BUNDLED WITH
    2.3.16