Add RSpec workflow

.github/workflows/rspec.yml

@@ -0,0 +1,23 @@
+name: Ruby
+
+on: [push, fork]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    name: Ruby ${{ matrix.ruby }}
+    strategy:
+      matrix:
+        ruby:  ['2.7', '3.0', '3.2']
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Set up Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby }}
+        bundler-cache: true
+
+    - name: Run rspec
+      run: bundle exec rake spec