Recomend podman instead of docker and remove mentions to Docker images

[picnixz]

Fixes #1441.

This also simplifies the instructions, removing the systemd part (because honestly, I think it could be more confusing than helping if someone is not using systemd or does not know how to use it...). Using podman is much simpler and if there's any issue we can help them directly in their PR.

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📚 Documentation preview 📚: https://cpython-devguide--1442.org.readthedocs.build/

[picnixz]

Concerning the creation of files owned by the root user by the docker service, this is something I encountered but not always. AFAIK, podman does not any super-user permissions and would not create files owned by root (I honestly don't know what happened).

[ezio-melotti]

FTR you can commit review suggestions directly from GitHub, either individually or in a single batch from the "files changed" tab.

[picnixz]

FTR you can commit review suggestions directly from GitHub, either individually or in a single batch from the "files changed" tab.

Yes I know, but I didn't commit your suggestion because I wanted to split the line somewhere else (just to make it more or less aligned with the rest of the paragraph). I also avoid to use the GH UI if I'm on my dev env since otherwise I need to remember to pull from my remote branch :')