add ci to check dependencies

Author: JoeWang1127

.github/workflows/ci.yaml

@@ -277,3 +277,11 @@ jobs:
       with:
         bom-path: gapic-generator-java-bom/pom.xml
 
+  bom_unmanaged_dependency_check:
+    runs-on: ubuntu-22.04
+    steps:
+    - uses: actions/checkout@v3
+    - name: Unmanaged dependency check
+      uses: java-shared-dependencies/unmanaged-dependency-check
+      with:
+        bom-path: gapic-generator-java-bom/pom.xml