Fixing scatter plot size (#32904)
This fixes the marker size in scatter plots (see https://github.com/pandas-dev/pandas/issues/32904).

- [x] closes #32904
- [ ] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Can you add a test for this? In `pandas/tests/plotting/test_frame.py` Your original example should be fine. That should have a comment referring back to your issue.

And we'll need a release note in whatsnew/v1.1.0.rst. I made some errors with merging the commits and ended up deleting the original fork. Not sure if it's possible to adjust this pull request, so will create a new one instead.