fix: Gemfile.lock & Gemfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-FFI-22037
- https://snyk.io/vuln/SNYK-RUBY-NOKOGIRI-72433

Author: snyk-bot

Gemfile

@@ -1,3 +1,3 @@
 source "https://rubygems.org"
 
-gem 'github-pages'
+gem 'github-pages', '>= 150'

Gemfile.lock

@@ -1,183 +1,227 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (4.2.8)
+    activesupport (4.2.10)
       i18n (~> 0.7)
       minitest (~> 5.1)
       thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
-    addressable (2.5.1)
-      public_suffix (~> 2.0, >= 2.0.2)
+    addressable (2.5.2)
+      public_suffix (>= 2.0.2, < 4.0)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
-    coffee-script-source (1.12.2)
+    coffee-script-source (1.11.1)
     colorator (1.1.0)
-    ethon (0.10.1)
+    commonmarker (0.17.13)
+      ruby-enum (~> 0.5)
+    concurrent-ruby (1.1.3)
+    dnsruby (1.61.2)
+      addressable (~> 2.5)
+    em-websocket (0.5.1)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0.6.0)
+    ethon (0.11.0)
       ffi (>= 1.3.0)
+    eventmachine (1.2.7)
     execjs (2.7.0)
-    faraday (0.12.2)
+    faraday (0.15.3)
       multipart-post (>= 1.2, < 3)
-    ffi (1.9.18)
+    ffi (1.9.25)
     forwardable-extended (2.6.0)
     gemoji (3.0.0)
-    github-pages (150)
-      activesupport (= 4.2.8)
-      github-pages-health-check (= 1.3.5)
-      jekyll (= 3.5.1)
-      jekyll-avatar (= 0.4.2)
-      jekyll-coffeescript (= 1.0.1)
+    github-pages (192)
+      activesupport (= 4.2.10)
+      github-pages-health-check (= 1.8.1)
+      jekyll (= 3.7.4)
+      jekyll-avatar (= 0.6.0)
+      jekyll-coffeescript (= 1.1.1)
+      jekyll-commonmark-ghpages (= 0.1.5)
       jekyll-default-layout (= 0.1.4)
-      jekyll-feed (= 0.9.2)
-      jekyll-gist (= 1.4.1)
-      jekyll-github-metadata (= 2.6.0)
-      jekyll-mentions (= 1.2.0)
-      jekyll-optional-front-matter (= 0.2.0)
+      jekyll-feed (= 0.10.0)
+      jekyll-gist (= 1.5.0)
+      jekyll-github-metadata (= 2.9.4)
+      jekyll-mentions (= 1.4.1)
+      jekyll-optional-front-matter (= 0.3.0)
       jekyll-paginate (= 1.1.0)
-      jekyll-readme-index (= 0.1.0)
-      jekyll-redirect-from (= 0.12.1)
-      jekyll-relative-links (= 0.4.1)
-      jekyll-sass-converter (= 1.5.0)
-      jekyll-seo-tag (= 2.2.3)
-      jekyll-sitemap (= 1.0.0)
+      jekyll-readme-index (= 0.2.0)
+      jekyll-redirect-from (= 0.14.0)
+      jekyll-relative-links (= 0.5.3)
+      jekyll-remote-theme (= 0.3.1)
+      jekyll-sass-converter (= 1.5.2)
+      jekyll-seo-tag (= 2.5.0)
+      jekyll-sitemap (= 1.2.0)
       jekyll-swiss (= 0.4.0)
-      jekyll-theme-architect (= 0.0.4)
-      jekyll-theme-cayman (= 0.0.4)
-      jekyll-theme-dinky (= 0.0.4)
-      jekyll-theme-hacker (= 0.0.4)
-      jekyll-theme-leap-day (= 0.0.4)
-      jekyll-theme-merlot (= 0.0.4)
-      jekyll-theme-midnight (= 0.0.4)
-      jekyll-theme-minimal (= 0.0.4)
-      jekyll-theme-modernist (= 0.0.4)
-      jekyll-theme-primer (= 0.4.0)
-      jekyll-theme-slate (= 0.0.4)
-      jekyll-theme-tactile (= 0.0.4)
-      jekyll-theme-time-machine (= 0.0.4)
-      jekyll-titles-from-headings (= 0.4.0)
-      jemoji (= 0.8.0)
-      kramdown (= 1.13.2)
+      jekyll-theme-architect (= 0.1.1)
+      jekyll-theme-cayman (= 0.1.1)
+      jekyll-theme-dinky (= 0.1.1)
+      jekyll-theme-hacker (= 0.1.1)
+      jekyll-theme-leap-day (= 0.1.1)
+      jekyll-theme-merlot (= 0.1.1)
+      jekyll-theme-midnight (= 0.1.1)
+      jekyll-theme-minimal (= 0.1.1)
+      jekyll-theme-modernist (= 0.1.1)
+      jekyll-theme-primer (= 0.5.3)
+      jekyll-theme-slate (= 0.1.1)
+      jekyll-theme-tactile (= 0.1.1)
+      jekyll-theme-time-machine (= 0.1.1)
+      jekyll-titles-from-headings (= 0.5.1)
+      jemoji (= 0.10.1)
+      kramdown (= 1.17.0)
       liquid (= 4.0.0)
-      listen (= 3.0.6)
+      listen (= 3.1.5)
       mercenary (~> 0.3)
-      minima (= 2.1.1)
-      rouge (= 1.11.1)
+      minima (= 2.5.0)
+      nokogiri (>= 1.8.2, < 2.0)
+      rouge (= 2.2.1)
       terminal-table (~> 1.4)
-    github-pages-health-check (1.3.5)
+    github-pages-health-check (1.8.1)
       addressable (~> 2.3)
-      net-dns (~> 0.8)
+      dnsruby (~> 1.60)
       octokit (~> 4.0)
       public_suffix (~> 2.0)
-      typhoeus (~> 0.7)
-    html-pipeline (2.6.0)
+      typhoeus (~> 1.3)
+    html-pipeline (2.8.4)
       activesupport (>= 2)
       nokogiri (>= 1.4)
-    i18n (0.8.6)
-    jekyll (3.5.1)
+    http_parser.rb (0.6.0)
+    i18n (0.9.5)
+      concurrent-ruby (~> 1.0)
+    jekyll (3.7.4)
       addressable (~> 2.4)
       colorator (~> 1.0)
+      em-websocket (~> 0.5)
+      i18n (~> 0.7)
       jekyll-sass-converter (~> 1.0)
-      jekyll-watch (~> 1.1)
-      kramdown (~> 1.3)
+      jekyll-watch (~> 2.0)
+      kramdown (~> 1.14)
       liquid (~> 4.0)
       mercenary (~> 0.3.3)
       pathutil (~> 0.9)
-      rouge (~> 1.7)
+      rouge (>= 1.7, < 4)
       safe_yaml (~> 1.0)
-    jekyll-avatar (0.4.2)
+    jekyll-avatar (0.6.0)
       jekyll (~> 3.0)
-    jekyll-coffeescript (1.0.1)
+    jekyll-coffeescript (1.1.1)
       coffee-script (~> 2.2)
+      coffee-script-source (~> 1.11.1)
+    jekyll-commonmark (1.2.0)
+      commonmarker (~> 0.14)
+      jekyll (>= 3.0, < 4.0)
+    jekyll-commonmark-ghpages (0.1.5)
+      commonmarker (~> 0.17.6)
+      jekyll-commonmark (~> 1)
+      rouge (~> 2)
     jekyll-default-layout (0.1.4)
       jekyll (~> 3.0)
-    jekyll-feed (0.9.2)
+    jekyll-feed (0.10.0)
       jekyll (~> 3.3)
-    jekyll-gist (1.4.1)
+    jekyll-gist (1.5.0)
       octokit (~> 4.2)
-    jekyll-github-metadata (2.6.0)
+    jekyll-github-metadata (2.9.4)
       jekyll (~> 3.1)
       octokit (~> 4.0, != 4.4.0)
-    jekyll-mentions (1.2.0)
-      activesupport (~> 4.0)
+    jekyll-mentions (1.4.1)
       html-pipeline (~> 2.3)
       jekyll (~> 3.0)
-    jekyll-optional-front-matter (0.2.0)
+    jekyll-optional-front-matter (0.3.0)
       jekyll (~> 3.0)
     jekyll-paginate (1.1.0)
-    jekyll-readme-index (0.1.0)
+    jekyll-readme-index (0.2.0)
       jekyll (~> 3.0)
-    jekyll-redirect-from (0.12.1)
+    jekyll-redirect-from (0.14.0)
       jekyll (~> 3.3)
-    jekyll-relative-links (0.4.1)
+    jekyll-relative-links (0.5.3)
       jekyll (~> 3.3)
-    jekyll-sass-converter (1.5.0)
+    jekyll-remote-theme (0.3.1)
+      jekyll (~> 3.5)
+      rubyzip (>= 1.2.1, < 3.0)
+    jekyll-sass-converter (1.5.2)
       sass (~> 3.4)
-    jekyll-seo-tag (2.2.3)
+    jekyll-seo-tag (2.5.0)
       jekyll (~> 3.3)
-    jekyll-sitemap (1.0.0)
+    jekyll-sitemap (1.2.0)
       jekyll (~> 3.3)
     jekyll-swiss (0.4.0)
-    jekyll-theme-architect (0.0.4)
-      jekyll (~> 3.3)
-    jekyll-theme-cayman (0.0.4)
-      jekyll (~> 3.3)
-    jekyll-theme-dinky (0.0.4)
-      jekyll (~> 3.3)
-    jekyll-theme-hacker (0.0.4)
-      jekyll (~> 3.3)
-    jekyll-theme-leap-day (0.0.4)
-      jekyll (~> 3.3)
-    jekyll-theme-merlot (0.0.4)
-      jekyll (~> 3.3)
-    jekyll-theme-midnight (0.0.4)
-      jekyll (~> 3.3)
-    jekyll-theme-minimal (0.0.4)
-      jekyll (~> 3.3)
-    jekyll-theme-modernist (0.0.4)
-      jekyll (~> 3.3)
-    jekyll-theme-primer (0.4.0)
+    jekyll-theme-architect (0.1.1)
       jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.2)
-    jekyll-theme-slate (0.0.4)
-      jekyll (~> 3.3)
-    jekyll-theme-tactile (0.0.4)
-      jekyll (~> 3.3)
-    jekyll-theme-time-machine (0.0.4)
-      jekyll (~> 3.3)
-    jekyll-titles-from-headings (0.4.0)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-cayman (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-dinky (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-hacker (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-leap-day (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-merlot (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-midnight (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-minimal (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-modernist (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-primer (0.5.3)
+      jekyll (~> 3.5)
+      jekyll-github-metadata (~> 2.9)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-slate (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-tactile (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-time-machine (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-titles-from-headings (0.5.1)
       jekyll (~> 3.3)
-    jekyll-watch (1.5.0)
-      listen (~> 3.0, < 3.1)
-    jemoji (0.8.0)
-      activesupport (~> 4.0)
+    jekyll-watch (2.1.2)
+      listen (~> 3.0)
+    jemoji (0.10.1)
       gemoji (~> 3.0)
       html-pipeline (~> 2.2)
-      jekyll (>= 3.0)
-    kramdown (1.13.2)
+      jekyll (~> 3.0)
+    kramdown (1.17.0)
     liquid (4.0.0)
-    listen (3.0.6)
-      rb-fsevent (>= 0.9.3)
-      rb-inotify (>= 0.9.7)
+    listen (3.1.5)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
+      ruby_dep (~> 1.2)
     mercenary (0.3.6)
     mini_portile2 (2.3.0)
-    minima (2.1.1)
-      jekyll (~> 3.3)
-    minitest (5.10.3)
+    minima (2.5.0)
+      jekyll (~> 3.5)
+      jekyll-feed (~> 0.9)
+      jekyll-seo-tag (~> 2.1)
+    minitest (5.11.3)
     multipart-post (2.0.0)
-    net-dns (0.8.0)
-    nokogiri (1.8.2)
+    nokogiri (1.8.5)
       mini_portile2 (~> 2.3.0)
-    octokit (4.7.0)
+    octokit (4.13.0)
       sawyer (~> 0.8.0, >= 0.5.3)
-    pathutil (0.14.0)
+    pathutil (0.16.2)
       forwardable-extended (~> 2.6)
     public_suffix (2.0.5)
-    rb-fsevent (0.10.2)
+    rb-fsevent (0.10.3)
     rb-inotify (0.9.10)
       ffi (>= 0.5.0, < 2)
-    rouge (1.11.1)
+    rouge (2.2.1)
+    ruby-enum (0.7.2)
+      i18n
+    ruby_dep (1.5.0)
+    rubyzip (1.2.2)
     safe_yaml (1.0.4)
-    sass (3.5.1)
+    sass (3.7.1)
       sass-listen (~> 4.0.0)
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
@@ -188,17 +232,17 @@ GEM
     terminal-table (1.8.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
     thread_safe (0.3.6)
-    typhoeus (0.8.0)
-      ethon (>= 0.8.0)
-    tzinfo (1.2.3)
+    typhoeus (1.3.1)
+      ethon (>= 0.9.0)
+    tzinfo (1.2.5)
       thread_safe (~> 0.1)
-    unicode-display_width (1.3.0)
+    unicode-display_width (1.4.0)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  github-pages
+  github-pages (>= 150)
 
 BUNDLED WITH
-   1.16.1
+   1.16.6