fix: Gemfile & Gemfile.lock to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-NOKOGIRI-8732769
- https://snyk.io/vuln/SNYK-RUBY-NOKOGIRI-8732779

Author: snyk-bot

Gemfile

@@ -1,5 +1,5 @@
 source "https://rubygems.org"
 
 gem 'github-pages', '>= 201'
-gem 'html-proofer', '>= 3.13.0'
+gem 'html-proofer', '>= 3.15.0'
 gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw]

Gemfile.lock

@@ -6,8 +6,8 @@ GEM
       minitest (~> 5.1)
       thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
-    addressable (2.7.0)
-      public_suffix (>= 2.0.2, < 5.0)
+    addressable (2.8.7)
+      public_suffix (>= 2.0.2, < 7.0)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
@@ -21,13 +21,13 @@ GEM
     em-websocket (0.5.1)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
-    ethon (0.12.0)
-      ffi (>= 1.3.0)
+    ethon (0.16.0)
+      ffi (>= 1.15.0)
     eventmachine (1.2.7)
     execjs (2.7.0)
     faraday (0.17.0)
       multipart-post (>= 1.2, < 3)
-    ffi (1.11.2)
+    ffi (1.17.1)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
     github-pages (202)
@@ -84,14 +84,15 @@ GEM
     html-pipeline (2.12.2)
       activesupport (>= 2)
       nokogiri (>= 1.4)
-    html-proofer (3.14.1)
+    html-proofer (4.4.3)
       addressable (~> 2.3)
       mercenary (~> 0.3)
-      nokogiri (~> 1.10)
-      parallel (~> 1.3)
+      nokogiri (~> 1.13)
+      parallel (~> 1.10)
       rainbow (~> 3.0)
       typhoeus (~> 1.3)
       yell (~> 2.0)
+      zeitwerk (~> 2.5)
     http_parser.rb (0.6.0)
     i18n (0.9.5)
       concurrent-ruby (~> 1.0)
@@ -207,22 +208,24 @@ GEM
       rb-inotify (~> 0.9, >= 0.9.7)
       ruby_dep (~> 1.2)
     mercenary (0.3.6)
-    mini_portile2 (2.4.0)
+    mini_portile2 (2.8.8)
     minima (2.5.0)
       jekyll (~> 3.5)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
     minitest (5.13.0)
     multipart-post (2.1.1)
-    nokogiri (1.10.8)
-      mini_portile2 (~> 2.4.0)
+    nokogiri (1.15.7)
+      mini_portile2 (~> 2.8.2)
+      racc (~> 1.4)
     octokit (4.14.0)
       sawyer (~> 0.8.0, >= 0.5.3)
-    parallel (1.19.0)
+    parallel (1.26.3)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
     public_suffix (3.1.1)
-    rainbow (3.0.0)
+    racc (1.8.1)
+    rainbow (3.1.1)
     rb-fsevent (0.10.3)
     rb-inotify (0.10.0)
       ffi (~> 1.0)
@@ -243,19 +246,20 @@ GEM
     terminal-table (1.8.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
     thread_safe (0.3.6)
-    typhoeus (1.3.1)
+    typhoeus (1.4.1)
       ethon (>= 0.9.0)
     tzinfo (1.2.5)
       thread_safe (~> 0.1)
     unicode-display_width (1.6.0)
-    yell (2.2.0)
+    yell (2.2.2)
+    zeitwerk (2.6.18)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
   github-pages (>= 201)
-  html-proofer (>= 3.13.0)
+  html-proofer (>= 3.15.0)
   tzinfo-data
 
 BUNDLED WITH