Add Ruby 3.4 to CI (#20)

Add Ruby 3.4 to CI
Also use --enable-frozen-string-literal in CI to ensure compatibility

Author: westonganger

.github/workflows/test.yml

@@ -23,6 +23,7 @@ jobs:
           - ruby: "3.1"
           - ruby: "3.2"
           - ruby: "3.3"
+          - ruby: "3.4"
           ### TEST RAILS VERSIONS
           - ruby: "2.6"
             rails_version: "~> 6.0.0"
@@ -31,11 +32,11 @@ jobs:
           - ruby: "3.3"
             rails_version: "~> 7.0.0"
             db_gem_version: "~> 1.4" # fixes sqlite3 gem dependency issue
-          - ruby: "3.3"
+          - ruby: "3.4"
             rails_version: "~> 7.1.0"
-          - ruby: "3.3"
+          - ruby: "3.4"
             rails_version: "~> 7.2.0"
-          - ruby: "3.3"
+          - ruby: "3.4"
             rails_version: "~> 8.0.0"
 
     steps:
@@ -58,4 +59,4 @@ jobs:
         bundle install
         bundle exec rake db:create
         bundle exec rake db:migrate
-        bundle exec rake test
+        RUBYOPT='--enable-frozen-string-literal' bundle exec rake test