Update docs and ci due to new PiOS release

[AlvinSchiller]

PiOS Trixie got released in October.

This invalidates some aspects of the docs (e.g. PiOs legacy for the current state).

Todos:

• release develop branch(es)
• update ci for trixie
• update docs

[s-martin]

In addition we should try to release V2 to bring the fixes from develop to users.

[AlvinSchiller]

In addition we should try to release V2 to bring the fixes from develop to users.

Yep, that was the first point about. This also needs to be done for v3.

I try to look into this, this week.