deps: update googleapis/java-cloud-bom digest to 4b9b60d (#2178)

Author: renovate-bot

.github/workflows/ci.yaml

@@ -282,7 +282,7 @@ jobs:
       run: |
         mvn install -B -ntp -DskipTests -Dclirr.skip -Dcheckstyle.skip
     - name: Validate gapic-generator-java-bom
-      uses: googleapis/java-cloud-bom/tests/validate-bom@e485c2f4ca9ec4f06098e23ee4a24b94ff193784
+      uses: googleapis/java-cloud-bom/tests/validate-bom@4b9b60df0e240de0f3ac6ad729d53de2039ad0ef
       with:
         bom-path: gapic-generator-java-bom/pom.xml