build: point to right unmanaged dep check

Author: diegomarquezp

.github/workflows/unmanaged-dependency-check.yaml

@@ -14,6 +14,6 @@ jobs:
       shell: bash
       run: .kokoro/build.sh
     - name: Unmanaged dependency check
-      uses: googleapis/sdk-platform-java/java-shared-dependencies/unmanaged-dependency-check@google-cloud-shared-dependencies/v3.58.0
+      uses: googleapis/google-cloud-java/sdk-platform-java/java-shared-dependencies/unmanaged-dependency-check@v1.85.0
       with:
         bom-path: google-cloud-firestore-bom/pom.xml