Revert "build(owl-bot): temporarily disable signature verification (#3392)" (#3393)
Revert "build(owl-bot): temporarily disable signature verification (#3392)" (#3393)

This reverts commit dc663c1cae3c3e016192b6ebbcd4b5b9f332137d.
googleapis/repo-automation-bots,googleapis/repo-automation-bots,googleapis/repo-automation-bots,googleapis/repo-automation-bots,googleapis/repo-automation-bots