improve release process

[pmeier]

Currently, I'm manually creating and publishing releases. This has two downsides:

1. Releasing involves quite a few steps. Doing them manually opens up the window for mistakes.
2. All the knowledge on how to release currently is in my head and not documented anywhere else. If I'm unable to do a release for some reason, others will have a hard time replicating my process.

To overcome this, I propose two things:

1. Automate as much as possible through GitHub Actions.
2. Write up the release process in the documentation so everyone with the right permissions can do it.

[arjxn-py]

A build workflow has already been created for both ragna & ragna-base in #405 which can further be extended to publish the built wheels plus the same can be documented as well.