Update version of pylint to 3.3.3 (#845)

This updates `requirements.txt` to use Pylint version 3.3.3 and also
updates `.pylintrc` such that it's compatible with 3.3.3 yet does not
raise any new warnings in the code base. The intention of this PR is to
make only the minimal changes needed to use pylint 3.3.3.

The `.pylintrc` started life as the config file produced by pylint 3.3.3
with the `--generate-rcfile` option. I then compared it to the previous
`.pylintrc` and adjusted the settings to match, followed by a long
period of test-adjust-retest:

1. run `pylint` on the existing code base
2. look at the warnings, find the relevant flags & turn them off
3. if there are more warnings, go back to step 1

This `.pylintrc` file thus has a lot of pylint checkers commented out.
We should systematically re-enable the checkers and fix the warnings in
the code. However, that should be left to separate PRs.

Author: mhucka