TST: IntegerNA Support for DataFrame.diff()
- [x] closes #24171
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Test for IntegerNA support DataFrame.diff().
``` bash
pytest tests/frame/methods/test_diff.py::TestDataFrameDiff::test_diff_integer_na
```

looks good (will merge shortly, trying to get master to run first). thanks @Marvzinc 