deps: update googleapis/java-cloud-bom digest to ef3656d (#3630)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| googleapis/java-cloud-bom | action | digest | `47ad868` → `ef3656d` |

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Author: renovate-bot

.github/workflows/ci.yaml

@@ -417,7 +417,7 @@ jobs:
       run: |
         mvn install -B -ntp -DskipTests -Dclirr.skip -Dcheckstyle.skip -Dfmt.skip
     - name: Validate gapic-generator-java-bom
-      uses: googleapis/java-cloud-bom/tests/validate-bom@47ad868794c5d38ee7eb95d69371a7a79f84d890
+      uses: googleapis/java-cloud-bom/tests/validate-bom@ef3656d3c66f4c6bd3b2c569d64a77cb40aeb77e
       with:
         bom-path: gapic-generator-java-bom/pom.xml