fix: Gemfile & Gemfile.lock to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-RUBYZIP-469156

Gemfile

@@ -1,5 +1,5 @@
 source "https://rubygems.org"
 
-gem 'github-pages', '>= 148'
+gem 'github-pages', '>= 198'
 gem 'html-proofer', '>= 3.11.1'
 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 (2.6.0)
-      public_suffix (>= 2.0.2, < 4.0)
+    addressable (2.7.0)
+      public_suffix (>= 2.0.2, < 5.0)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
@@ -16,7 +16,7 @@ GEM
     commonmarker (0.17.13)
       ruby-enum (~> 0.5)
     concurrent-ruby (1.1.5)
-    dnsruby (1.61.2)
+    dnsruby (1.61.3)
       addressable (~> 2.5)
     em-websocket (0.5.1)
       eventmachine (>= 0.12.9)
@@ -25,12 +25,12 @@ GEM
       ffi (>= 1.3.0)
     eventmachine (1.2.7)
     execjs (2.7.0)
-    faraday (0.15.4)
+    faraday (0.16.2)
       multipart-post (>= 1.2, < 3)
     ffi (1.11.1)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
-    github-pages (198)
+    github-pages (200)
       activesupport (= 4.2.11.1)
       github-pages-health-check (= 1.16.1)
       jekyll (= 3.8.5)
@@ -47,7 +47,7 @@ GEM
       jekyll-readme-index (= 0.2.0)
       jekyll-redirect-from (= 0.14.0)
       jekyll-relative-links (= 0.6.0)
-      jekyll-remote-theme (= 0.3.1)
+      jekyll-remote-theme (= 0.4.0)
       jekyll-sass-converter (= 1.5.2)
       jekyll-seo-tag (= 2.5.0)
       jekyll-sitemap (= 1.2.0)
@@ -72,7 +72,7 @@ GEM
       listen (= 3.1.5)
       mercenary (~> 0.3)
       minima (= 2.5.0)
-      nokogiri (>= 1.8.5, < 2.0)
+      nokogiri (>= 1.10.4, < 2.0)
       rouge (= 2.2.1)
       terminal-table (~> 1.4)
     github-pages-health-check (1.16.1)
@@ -142,7 +142,8 @@ GEM
       jekyll (~> 3.3)
     jekyll-relative-links (0.6.0)
       jekyll (~> 3.3)
-    jekyll-remote-theme (0.3.1)
+    jekyll-remote-theme (0.4.0)
+      addressable (~> 2.0)
       jekyll (~> 3.5)
       rubyzip (>= 1.2.1, < 3.0)
     jekyll-sass-converter (1.5.2)
@@ -212,7 +213,7 @@ GEM
       jekyll (~> 3.5)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
-    minitest (5.11.3)
+    minitest (5.12.2)
     multipart-post (2.1.1)
     nokogiri (1.10.4)
       mini_portile2 (~> 2.4.0)
@@ -230,7 +231,7 @@ GEM
     ruby-enum (0.7.2)
       i18n
     ruby_dep (1.5.0)
-    rubyzip (1.2.3)
+    rubyzip (2.0.0)
     safe_yaml (1.0.5)
     sass (3.7.4)
       sass-listen (~> 4.0.0)
@@ -254,9 +255,9 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
-  github-pages (>= 148)
+  github-pages (>= 198)
   html-proofer (>= 3.11.1)
   tzinfo-data
 
 BUNDLED WITH
-   2.0.2
+   1.17.3