Use ruby3 for build

Author: benjeffery

.github/workflows/build-core.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Set up Ruby 2.7
         uses: ruby/[email protected]
         with:
-          ruby-version: '2.7'
+          ruby-version: '3.1'
           bundler-cache: true # runs 'bundle install' and caches installed gems automatically
 
       - uses: actions/[email protected]

Gemfile

@@ -44,4 +44,7 @@ gem 'jekyll-font-awesome-sass'
 gem "hash-joiner"
 gem "open-uri-cached"
 gem "httparty"
-gem 'jekyll-redirect-from'
+gem 'jekyll-redirect-from'
+
+# Fix for Ruby 3.0+ compatibility
+gem "rexml"

Gemfile.lock

@@ -80,6 +80,7 @@ GEM
     rb-fsevent (0.11.1)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
+    rexml (3.4.2)
     rouge (3.29.0)
     safe_yaml (1.0.5)
     sass (3.7.4)
@@ -114,6 +115,7 @@ DEPENDENCIES
   jekyll-timeago
   minima (~> 2.0)
   open-uri-cached
+  rexml
   tzinfo (~> 1.2)
   tzinfo-data
   wdm (~> 0.1.0)