update ruby version in tests to match gh pages version

.github/workflows/test.yml

@@ -19,7 +19,7 @@ jobs:
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:
-        ruby-version: 2.7.4
+        ruby-version: 3.3.4
         bundler-cache: true
 
     - name: Run tests

.rubocop.yml

@@ -1,6 +1,6 @@
 AllCops:
   NewCops: enable
-  TargetRubyVersion: 2.7
+  TargetRubyVersion: 3.3
   Exclude:
     - _site/**/*
     - vendor/**/*