Refactoring: Force ruff static checker for project

[penguinolog]

• do not use assert in production code
• package files are not executable
• use isinstance
• stop checks like if boolean == True: ...
• use contextlib.suppress
• explicit return None in optionals
• reduce amount of shadowed keywords (next, ...)

Checklist

• I've ensured that similar functionality has not already been implemented
• I've ensured that similar functionality has not earlier been proposed and declined
• I've branched off the master or python-dual-support branch
• I've merged fresh upstream into my branch recently
• I've ran tox successfully in local environment
• I've included docstrings and/or documentation and/or examples for my code (if this is a new feature)

[coveralls]

Pull Request Test Coverage Report for Build 6323621144

• 203 of 418 (48.56%) changed or added relevant lines in 11 files are covered.
• 6 unchanged lines in 4 files lost coverage.
• Overall coverage increased (+0.3%) to 74.386%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
urwid/monitored_list.py	0	1	0.0%
urwid/signals.py	2	3	66.67%
urwid/vterm.py	22	30	73.33%
urwid/display_common.py	17	26	65.38%
urwid/util.py	14	24	58.33%
urwid/text_layout.py	45	66	68.18%
urwid/canvas.py	59	82	71.95%
urwid/listbox.py	38	71	53.52%
urwid/treetools.py	1	47	2.13%
urwid/raw_display.py	3	66	4.55%

Files with Coverage Reduction	New Missed Lines	%
urwid/canvas.py	1	84.95%
urwid/display_common.py	1	73.23%
urwid/text_layout.py	1	87.5%
urwid/treetools.py	3	20.9%

Totals
Change from base Build 6311553324:	0.3%
Covered Lines:	7518
Relevant Lines:	10290

---

💛 - Coveralls

[ulidtko]

@penguinolog you should give more time for code review. 4 minutes between opening a +755 −698 PR and insta-merging it — is not sufficient to post even a short comment.

[penguinolog]

I agree, but this PR from hell was 90% automatically generated

[ulidtko]

That's even worse.

Source code is for humans to read.

[neiljp]

It's great to see this extra linting of the project, but I'd agree re reviewing. Personally, I'd break these automated changes into multiple commits, each linting/fixing additional aspects.