Sign published image manifests with cosign#376

Wuodan wants to merge 6 commits intonikolaik:mainnikolaik/docker-python-nodejs:mainfrom

Wuodan:upstream-PR/03-sign-image-manifests-with-cosignWuodan/docker-python-nodejs:upstream-PR/03-sign-image-manifests-with-cosignCopy head branch name to clipboard