Avoid use of `release-by-pr-label` Action

[guineveresaenger]

We tell users to use a public Action that uses release-bot, a provate repository meant for internal use at Pulumi.

We should find a way to avoid shipping this dependency.

https://github.com/search?q=repo%3Apulumi%2Fpulumi-tf-provider-boilerplate%20release-by-pr&type=code

See alse: pulumi/action-release-by-pr-label#11