Code cleanups

[c4rlo]

• a4b020a addresses some minor issues I found via the ruff linter.
• 1449745 addresses a circular dependency I noticed between the uwsm.misc and uwsm.dbus modules. This didn't seem to cause a problem in practice, but doesn't seem like a good idea. The price for fixing it is removal of a print_debug() statement in DbusInteractions.__init__(). If this is not acceptable, we can look for alternative solutions.

[Vladimir-csp]

Thanks!
I would like to continue splitting stuff into modules (#16), so I need a way to cross-import between them. Printing/notification functions in misc require dbus functinons, and dbus functions may need to use functions from misc. There is only one print_debug() call there because I added as a test with intention to add more.

What would be the best way to achieve that? I'm open to ideas.

[c4rlo]

Options I can think of:

1. Pull out print_debug() into its own module (e.g. debug.py) that has no dependencies, import that from everywhere else it's needed. Small downside is that it causes print_debug() to then live in a different module than the other print* functions, which is maybe a bit odd.
2. Merge misc.py and dbus.py into one module. Goes against the goal of more modularisation.
3. Inject the DBus dependency into the print* functions somehow, rather than having them explicitly depend on it. E.g. instead of taking a notify argument, they could get an optional notifier argument, where the caller may pass a DbusInteractions object (or None).

[c4rlo]

I have submitted #58 as an alternative to this PR. Feel free to close this one. The modularisation discussion can continue in #16, I think.

[Vladimir-csp]

Thanks!