Update RubyGems to fix Ruby 2.5 psych compatibility issue. (#28)

Author: ioquatix

.github/workflows/test.yaml

@@ -29,6 +29,9 @@ jobs:
           - "3.2"
           - "3.3"
 
+        rubygems:
+          - latest
+        
         experimental: [false]
 
         include:
@@ -37,6 +40,7 @@ jobs:
             experimental: true
           - os: ubuntu
             ruby: jruby
+            rubygems: default
             experimental: true
           - os: ubuntu
             ruby: head
@@ -50,6 +54,7 @@ jobs:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
       with:
+        rubygems: ${{matrix.rubygems}}
         ruby-version: ${{matrix.ruby}}
         bundler-cache: true