A release workflow

[KotlinIsland]

Scheduled job that detects release branches upstream then:

1. Creates a pr merging the base of said branch into master
2. Creates a release branch including the upstream release branch, and draft release on GitHub.
3. When the draft release is published pypi and docs are also published.

Also, when the version number changes, the release process is activated (for a bug fix release in a release branch)