Enable specs in CI

Author: headius

.github/workflows/maven.yml

@@ -27,8 +27,14 @@ jobs:
         java-version: '8'
         distribution: 'temurin'
         cache: maven
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: 'jruby'
+        bundler-cache: true
     - name: Build with Maven
       run: mvn -B install --file pom.xml
+    - name: Run specs
+      run: rake spec
 
     # Uploads the full dependency graph to GitHub to improve the quality of Dependabot alerts this repository can receive
     - name: Update dependency graph