Automate krew updates

> Please consider setting up [Krew release automation](https://krew.sigs.k8s.io/docs/developer-guide/release/automating-updates/) which helps you skip manually making updates to your Krew manifests on each new version and send a pull request. It’s a GitHub workflow bot that can run every time you push a new tag. Those PRs are automatically approved. _Originally posted by @ahmetb in [#4385](https://github.com/kubernetes-sigs/krew-index/issues/4385#issuecomment-2631591755)_