CLN: remove trailing commas for black update
Working on: CLN remove unnecessary trailing commas to get ready for new version of black #35925.
Checked the following files to make sure they are ready for black :
 pandas/tests/scalar/timestamp/test_arithmetic.py
 pandas/tests/scalar/timestamp/test_constructors.py
 pandas/tests/series/methods/test_argsort.py
 pandas/tests/series/methods/test_convert_dtypes.py
 pandas/tests/series/methods/test_drop_duplicates.py
 pandas/tests/series/methods/test_interpolate.py
 pandas/tests/series/methods/test_unstack.py
 pandas/tests/series/test_cumulative.py
 pandas/tests/test_algos.py

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Thanks @cjlynch278 !