Polkit dependency is not really optional for the GUI

[sbraz]

Hi,
As reported here, the GUI does not start if Polkit is not installed.
There is a condition here that works:

rmlint/gui/shredder/views/editor.py

Lines 25 to 28 in 2711b84

	try:
	from gi.repository import Polkit
	except ImportError:
	Polkit = None

However, this condition is not optional:

rmlint/gui/shredder/__init__.py

Line 11 in 2711b84

gi.require_version('Polkit', '1.0')

Could you please look into making Polkit really optional?