Revamp the CI pipeline, including publishing

[LukeMathWalker]

For releasing, we switched to release-plz. It handles version updates in manifests, changelog maintainance and crates.io publishing, thus simplifying the overall workflow.

I'd like to avoid using an API token for publishing. We can instead rely on trusted publishing from GitHub Actions. The only prerequisite is a bit of configuration on the crates.io management panel (cc @oshadmi).

I switched the repository to using stable as the default toolchain. There does seem to be no need for nightly anywhere.

[oshadmi]

@LukeMathWalker using #429 #430 I could add myself as owner of redis-module and we could try setting up Trusted Publishing