DOC/BUG: Enforce that freq is required in Period.now
- [X] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [X] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [X] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.

xref pandas-dev/pandas-stubs#383 No. It looks optional but if not provided it raises.  This just makes it crystal clear that it is required.  Got it, thx. Could you fix pre-commit? @phofl Code check is fixed.   thx @bashtage 