Improve Release workflow

[fuzzypixelz]

Describe the release item

0. The current release workflow takes care of wheel builds for target platforms, followed by deployment to pypi.org
1. Creating a release branch, bumping the version and tagging it are done in an ad-hoc way (in out-of-tree scripts)
2. Read the Docs builds are triggered manually and new versions are also activated manually
3. GitHub releases are created manually
4. There is a zenoh-python directory on https://download.eclipse.org/zenoh but wheels are not uploaded there
5. Unlike Zenoh & plugins/backends, no Debian/Homebrew/Docker releases are done

The goal is to integrate (1), (2) and (3) in the release workflow. (4) and (5) will remain unaddressed unless there is a need for them arises.

[fuzzypixelz]

A new "Release" automation rule has been added in the Read the Docs project. It matches semantic version increments and sets them as default. Thus when the release branch is created with a tag, Read the Docs should build said version (thanks to the GitHub hook setup in eclipse-zenoh/.eclipsefdn#8) and make it the new "latest".

[fuzzypixelz]

The "Release" automation rule has been changed to only "activate" matched versions. We may have dry-runs that tag a branch commit under release/dry-run/* selected as latest, which is not what we want.

Thus the last step of selecting the Release number as the new latest is manual.