[ci] enable license check

Author: marmoure

.github/workflows/ci.yml

@@ -21,4 +21,6 @@ jobs:
       - name: Run Tests
         run: mvn -V -B test
       - name: Check JavaDoc
-        run: mvn -V -B javadoc:javadoc
+        run: mvn -V -B javadoc:javadoc
+      - name: Check License
+        run: mvn -V -B license:check