deps: update googleapis/sdk-platform-java action to v2.68.0#4389

rahul2393 merged 2 commits intogoogleapis:maingoogleapis/java-spanner:mainfrom

renovate-bot:renovate/googleapis-sdk-platform-java-2.xrenovate-bot/java-spanner:renovate/googleapis-sdk-platform-java-2.xCopy head branch name to clipboard