fix: Gemfile & Gemfile.lock to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-KRAMDOWN-585939

Gemfile

@@ -3,9 +3,9 @@ source 'https://rubygems.org'
 gem 'uswds-jekyll', :git => 'https://github.com/18F/uswds-jekyll.git'
 
 gem 'html-proofer'
-gem 'jekyll-sitemap'
+gem 'jekyll-sitemap', '>= 1.4.0'
 
 group :jekyll_plugins do
   gem 'jekyll_pages_api_search'
-  gem 'jemoji', '>= 0.11.1'
+  gem 'jemoji', '>= 0.12.0'
 end

Gemfile.lock

@@ -8,12 +8,11 @@ GIT
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (6.0.3.1)
+    activesupport (5.2.4.3)
       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)
       public_suffix (>= 2.0.2, < 5.0)
     colorator (1.1.0)
@@ -24,10 +23,10 @@ GEM
     ethon (0.12.0)
       ffi (>= 1.3.0)
     eventmachine (1.2.7)
-    ffi (1.12.2)
+    ffi (1.13.1)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
-    html-pipeline (2.12.3)
+    html-pipeline (2.13.0)
       activesupport (>= 2)
       nokogiri (>= 1.4)
     html-proofer (3.15.3)
@@ -79,7 +78,7 @@ GEM
     mercenary (0.3.6)
     mini_portile2 (2.4.0)
     minitest (5.14.1)
-    nokogiri (1.10.9)
+    nokogiri (1.10.10)
       mini_portile2 (~> 2.4.0)
     nokogumbo (2.0.2)
       nokogiri (~> 1.8, >= 1.8.4)
@@ -91,7 +90,7 @@ GEM
     rb-fsevent (0.10.4)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rouge (3.19.0)
+    rouge (3.21.0)
     safe_yaml (1.0.5)
     sass (3.7.4)
       sass-listen (~> 4.0.0)
@@ -104,16 +103,15 @@ GEM
     tzinfo (1.2.7)
       thread_safe (~> 0.1)
     yell (2.2.2)
-    zeitwerk (2.3.0)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
   html-proofer
-  jekyll-sitemap
+  jekyll-sitemap (>= 1.4.0)
   jekyll_pages_api_search
-  jemoji (>= 0.11.1)
+  jemoji (>= 0.12.0)
   uswds-jekyll!
 
 BUNDLED WITH