STYLE: Add pre-commit hook for debug statements
Added https://github.com/pre-commit/pre-commit-hooks#debug-statements as a pre-commit hook.

- [ ] closes #xxxx
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [ ] whatsnew entry
