Use latest RubyGems

or CI on edge Rails (7.1 that requires RubyGems >= 3.3.13)  would fail

Author: amatsuda

.github/workflows/ruby.yml

@@ -51,6 +51,7 @@ jobs:
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}
+          rubygems: latest
           bundler-cache: true # Run "bundle install", and cache the result automatically.
 
       - name: Ruby specs