Lock `miniconf-mqtt` python utilities to a tag

[ryan-summers]

Given that miniconf is undergoing heavy changes and development right now, the current main branch is incompatible with released miniconf versions. We should use a tag reference for the Python client similar to cargo.toml

[jordens]

Let's just release the miniconf client to pypi properly and install a specific version from there.

[jordens]

Done here in https://github.com/quartiq/stabilizer/commit/fdaa6d46ef7469b2081a4cfa461a57fc965218c7 but should just be a miniconf pypi release.

[ryan-summers]

Miniconf release is tracked in https://github.com/quartiq/miniconf/issues/136, but I'm not entirely sure it's even worth regular releases of Miniconf on Pypi. @jordens An alternative approach is to just keep the python dependency locked to the tag of the Miniconf version we're using and just avoiding PyPi.

I have nothing against releasing to PyPi, but it just feels like one more thing we need to keep track of, which is somewhat annoying. Maybe CI could automate the release process for us though

[jordens]

Agreed. Explicit dependency is fine.