Update ruby gem dependencies (#375)

Gemfile.lock

@@ -1,30 +1,30 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    addressable (2.8.0)
-      public_suffix (>= 2.0.2, < 5.0)
+    addressable (2.8.6)
+      public_suffix (>= 2.0.2, < 6.0)
     colorator (1.1.0)
-    concurrent-ruby (1.1.10)
+    concurrent-ruby (1.2.3)
     em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0)
-    ethon (0.15.0)
+    ethon (0.16.0)
       ffi (>= 1.15.0)
     eventmachine (1.2.7)
     eventmachine (1.2.7-x64-mingw32)
-    ffi (1.15.5)
-    ffi (1.15.5-x64-mingw32)
+    ffi (1.16.3)
+    ffi (1.16.3-x64-mingw32)
     forwardable-extended (2.6.0)
-    html-proofer (3.19.3)
+    html-proofer (3.19.4)
       addressable (~> 2.3)
       mercenary (~> 0.3)
-      nokogiri (~> 1.12)
-      parallel (~> 1.3)
+      nokogiri (~> 1.13)
+      parallel (~> 1.10)
       rainbow (~> 3.0)
       typhoeus (~> 1.3)
       yell (~> 2.0)
     http_parser.rb (0.8.0)
-    i18n (1.10.0)
+    i18n (1.14.1)
       concurrent-ruby (~> 1.0)
     jekyll (4.2.2)
       addressable (~> 2.4)
@@ -53,44 +53,44 @@ GEM
       jekyll (>= 3.7, < 5.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
-    kramdown (2.3.2)
+    kramdown (2.4.0)
       rexml
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
-    liquid (4.0.3)
-    listen (3.7.1)
+    liquid (4.0.4)
+    listen (3.8.0)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.4.0)
-    mini_portile2 (2.8.0)
-    nokogiri (1.13.6)
-      mini_portile2 (~> 2.8.0)
+    mini_portile2 (2.8.5)
+    nokogiri (1.15.5)
+      mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
-    nokogiri (1.13.6-x64-mingw32)
+    nokogiri (1.15.5-x64-mingw32)
       racc (~> 1.4)
-    parallel (1.22.0)
+    parallel (1.24.0)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (4.0.6)
-    racc (1.6.0)
+    public_suffix (5.0.4)
+    racc (1.7.3)
     rainbow (3.1.1)
-    rb-fsevent (0.11.1)
+    rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rexml (3.2.5)
-    rouge (3.28.0)
+    rexml (3.2.6)
+    rouge (3.30.0)
     safe_yaml (1.0.5)
     sassc (2.4.0)
       ffi (~> 1.9)
     sassc (2.4.0-x64-mingw32)
       ffi (~> 1.9)
     terminal-table (2.0.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
-    typhoeus (1.4.0)
+    typhoeus (1.4.1)
       ethon (>= 0.9.0)
     unicode-display_width (1.8.0)
     wdm (0.1.1)
-    webrick (1.7.0)
+    webrick (1.8.1)
     yell (2.2.2)
 
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