Fix pylint problems

[JiriPavela]

The codebase contains a lot of pylint errors and warnings. Some of them are rather minor, however, there are some more serious issues that should definitely be addressed. I'm adding a task list of pylint errors (sorted subjectively from the most to least severe) that should be resolved in a corresponding PR:

• Catching too broad exceptions. This can result in improper handling of unrelated exceptions.
• Explicitly specify the encoding when manipulating files PEP 597.
• Improper None comparison operators (== or != instead of is or is not).
• Unused variables (e.g., unused return values) should be denoted as _ to not pollute the namespace.
• Rewrite if-elif-else constructions with return statements inside.
• Unify string formatting, preferably using the f-strings.
• Improper usage of multiline strings as comments, or their improper location resulting in them not being recognized as docstrings.

For now, I'd suggest ignoring warnings related to missing docstrings, as that is much more time-consuming task warranting a standalone issue.