TYP: fix mypy ignored error in pandas/io/formats/latex.py
- [ ] xref #37715 
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Handle mypy ignored error in ``pandas/io/formats/latex.py``.
@simonjayhawkins looks like green (internal Windows py38_np18 error) Thanks @ivanovmg 