Add Ruby version matrix to test on both 3.4 and 4.0

Implements a GitHub Actions matrix strategy to test on multiple Ruby versions:
- Ruby 3.4 (current stable maintenance version)
- Ruby 4.0 (latest stable version)

Benefits:
- Ensures compatibility with both Ruby 3.4 and 4.0
- Catches Ruby version-specific issues early
- Demonstrates project works across Ruby versions
- Provides confidence for users on different Ruby versions
- fail-fast: false allows all versions to run even if one fails

The matrix runs tests in parallel, so CI time remains similar
while providing significantly more coverage.

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

Author: chorrell

.github/workflows/ruby.yml

@@ -3,18 +3,24 @@ name: Serverspec
 on: push
 
 jobs:
-  build:
-
+  test:
     runs-on: ubuntu-latest
+    
+    strategy:
+      matrix:
+        ruby-version: ['3.4', '4.0']
+      fail-fast: false
+
+    name: Ruby ${{ matrix.ruby-version }}
 
     steps:
     - uses: actions/checkout@v6
-    - name: Set up Ruby 3.4
+    - name: Set up Ruby ${{ matrix.ruby-version }}
       uses: ruby/setup-ruby@v1
       with:
-        ruby-version: 3.4
+        ruby-version: ${{ matrix.ruby-version }}
         bundler-cache: true
-    - name: Run test
+    - name: Run tests
       env:
         DOCKER_BUILDKIT: 1
       run: bundle exec rake