gem: use ruby version matrix

Author: q9f

.github/workflows/build.yml

@@ -12,11 +12,14 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby: ['3.3', '3.4']
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
       with:
-        ruby-version: 3.3
+        ruby-version: ${{ matrix.ruby }}
     - name: Install Dependencies
       run: |
         gem install test-unit

.github/workflows/codecl.yml

@@ -23,6 +23,7 @@ jobs:
         language:
           - ruby
           - c
+        ruby: ['3.3', '3.4']
     steps:
       - name: "Checkout repository"
         uses: actions/checkout@v4
@@ -36,7 +37,7 @@ jobs:
         uses: github/codeql-action/analyze@v3
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: '3.3'
+          ruby-version: ${{ matrix.ruby }}
           bundler-cache: true
       - name: "Run rufo code formatting checks"
         run: |