BUG-24915 fix unhashble Series.name in df aggregation
- [x] closes #24915
- [ ] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Before creating a pd.Series and pass {name} as argument, check if {name} is hashable. If not use default None.