enable pylint: literal-comparison
Issue #48855. This PR enables pylint type "R" warning: `literal-comparison`.
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
Hi @natmokval - if there's multiple codes which already pass, could you enable them all in the same PR please? Hi @MarcoGorelli.  Sure, next time I will make a single PR with all codes which passed.
Earlier today I created three separate PRs. Might be better to update this PR and include PR #49448 and PR #49449 in it? yeah that'd be good, thanks! All changes are added to this PR.