fix: Gemfile.lock to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-NOKOGIRI-2413994

Author: snyk-bot

Gemfile.lock

@@ -1,33 +1,33 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (6.0.3.1)
+    activesupport (6.0.4.6)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 0.7, < 2)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
       zeitwerk (~> 2.2, >= 2.2.2)
-    addressable (2.7.0)
+    addressable (2.8.0)
       public_suffix (>= 2.0.2, < 5.0)
     colorator (1.1.0)
-    concurrent-ruby (1.1.6)
-    em-websocket (0.5.1)
+    concurrent-ruby (1.1.9)
+    em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
-      http_parser.rb (~> 0.6.0)
+      http_parser.rb (~> 0)
     eventmachine (1.2.7)
     execjs (2.7.0)
     faraday (0.17.3)
       multipart-post (>= 1.2, < 3)
-    ffi (1.12.2)
+    ffi (1.15.5)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
-    html-pipeline (2.12.3)
+    html-pipeline (2.14.0)
       activesupport (>= 2)
       nokogiri (>= 1.4)
-    http_parser.rb (0.6.0)
-    i18n (1.8.2)
+    http_parser.rb (0.8.0)
+    i18n (1.10.0)
       concurrent-ruby (~> 1.0)
-    jekyll (4.0.0)
+    jekyll (4.0.1)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
@@ -46,9 +46,9 @@ GEM
       jekyll (>= 3.7, < 5.0)
     jekyll-gist (1.5.0)
       octokit (~> 4.2)
-    jekyll-octicons (9.5.0)
+    jekyll-octicons (16.3.1)
       jekyll (>= 3.6, < 5.0)
-      octicons (= 9.5.0)
+      octicons (= 16.3.1)
     jekyll-paginate (1.1.0)
     jekyll-relative-links (0.6.1)
       jekyll (>= 3.3, < 5.0)
@@ -63,9 +63,9 @@ GEM
       jekyll (>= 3.3, < 5.0)
     jekyll-sitemap (1.4.0)
       jekyll (>= 3.7, < 5.0)
-    jekyll-toc (0.13.1)
-      jekyll (>= 3.7)
-      nokogiri (~> 1.9)
+    jekyll-toc (0.17.1)
+      jekyll (>= 3.9)
+      nokogiri (~> 1.11)
     jekyll-twitter-plugin (2.1.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
@@ -75,59 +75,58 @@ GEM
       jekyll (>= 3.0, < 5.0)
     katex (0.6.0)
       execjs (~> 2.7)
-    kramdown (2.3.0)
+    kramdown (2.3.1)
       rexml
     kramdown-math-katex (1.0.1)
       katex (~> 0.4)
       kramdown (~> 2.0)
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
     liquid (4.0.3)
-    listen (3.2.1)
+    listen (3.7.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
-    mini_portile2 (2.5.0)
+    mini_portile2 (2.8.0)
     minima (2.5.1)
       jekyll (>= 3.5, < 5.0)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
-    minitest (5.14.1)
+    minitest (5.15.0)
     multipart-post (2.1.1)
-    nokogiri (1.11.1)
-      mini_portile2 (~> 2.5.0)
+    nokogiri (1.13.3)
+      mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
-    octicons (9.5.0)
-      nokogiri (>= 1.6.3.1)
+    octicons (16.3.1)
     octokit (4.16.0)
       faraday (>= 0.9)
       sawyer (~> 0.8.0, >= 0.5.3)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (4.0.3)
-    racc (1.5.2)
-    rb-fsevent (0.10.3)
+    public_suffix (4.0.6)
+    racc (1.6.0)
+    rb-fsevent (0.11.1)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rexml (3.2.4)
-    rouge (3.16.0)
+    rexml (3.2.5)
+    rouge (3.28.0)
     rubyzip (2.2.0)
     safe_yaml (1.0.5)
-    sassc (2.2.1)
+    sassc (2.4.0)
       ffi (~> 1.9)
     sawyer (0.8.2)
       addressable (>= 2.3.5)
       faraday (> 0.8, < 2.0)
     terminal-table (1.8.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
     thread_safe (0.3.6)
-    tzinfo (1.2.6)
+    tzinfo (1.2.9)
       thread_safe (~> 0.1)
     tzinfo-data (1.2019.3)
       tzinfo (>= 1.0.0)
-    unicode-display_width (1.6.1)
+    unicode-display_width (1.8.0)
     wdm (0.1.1)
-    zeitwerk (2.3.0)
+    zeitwerk (2.5.4)
 
 PLATFORMS
   ruby