fix: Gemfile & Gemfile.lock to reduce vulnerabilities (#104)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-REXML-12878608

Co-authored-by: snyk-bot <snyk-bot@snyk.io>

Author: camilamaia

Gemfile

@@ -4,4 +4,4 @@ source "https://rubygems.org"
 
 git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
 
-gem "jekyll", "~> 4.2.0"
+gem "jekyll", "~> 4.2.1"

Gemfile.lock

@@ -1,20 +1,20 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    addressable (2.8.0)
-      public_suffix (>= 2.0.2, < 5.0)
+    addressable (2.8.7)
+      public_suffix (>= 2.0.2, < 7.0)
     colorator (1.1.0)
-    concurrent-ruby (1.1.9)
-    em-websocket (0.5.2)
+    concurrent-ruby (1.3.5)
+    em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
-      http_parser.rb (~> 0.6.0)
+      http_parser.rb (~> 0)
     eventmachine (1.2.7)
-    ffi (1.15.3)
+    ffi (1.17.2)
     forwardable-extended (2.6.0)
-    http_parser.rb (0.6.0)
-    i18n (1.8.10)
+    http_parser.rb (0.8.0)
+    i18n (1.14.7)
       concurrent-ruby (~> 1.0)
-    jekyll (4.2.0)
+    jekyll (4.2.2)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
@@ -29,39 +29,39 @@ GEM
       rouge (~> 3.0)
       safe_yaml (~> 1.0)
       terminal-table (~> 2.0)
-    jekyll-sass-converter (2.1.0)
+    jekyll-sass-converter (2.2.0)
       sassc (> 2.0.1, < 3.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
-    kramdown (2.3.1)
-      rexml
+    kramdown (2.5.1)
+      rexml (>= 3.3.9)
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
-    liquid (4.0.3)
-    listen (3.5.1)
+    liquid (4.0.4)
+    listen (3.9.0)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.4.0)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (4.0.6)
-    rb-fsevent (0.11.0)
-    rb-inotify (0.10.1)
+    public_suffix (6.0.2)
+    rb-fsevent (0.11.2)
+    rb-inotify (0.11.1)
       ffi (~> 1.0)
-    rexml (3.3.9)
-    rouge (3.26.0)
+    rexml (3.4.4)
+    rouge (3.30.0)
     safe_yaml (1.0.5)
     sassc (2.4.0)
       ffi (~> 1.9)
     terminal-table (2.0.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
-    unicode-display_width (1.7.0)
+    unicode-display_width (1.8.0)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  jekyll (~> 4.2.0)
+  jekyll (~> 4.2.1)
 
 BUNDLED WITH
-   2.1.4
+   2.3.26