CLN: Use ABCNDFrame instead of ABCDataFrame and ABCSeries
- [ ] closes #xxxx
- [ ] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry
Thanks @jbrockmendel, for the pivot case, `NDFrame` was okay to import as well. My thinking is that `isinstance(obj, NDFrame)` is preferred over `isinstance(obj, (Series, DataFrame)`.