Compatibility with Python 3.11 typing system is wonky

[tungalbert99]

Something like the below works:

description: Optional[str] = None 

Something like the below doesn't work (supported by 3.11 which is equivalent)

description: str | None = None

which throws the error ERROR: A union composing a subcommand must all be of type BaseModel

[tungalbert99]

#32 addressed here

[sander76]

thanks for the fix!