allow Path object to be passed as default

[Kobu]

What is the problem that this PR addresses?

More often than not, when we prompt the user for a path, we later construct a builtin Path object from the received string. Following this notion, it is only logical that such object can also be passed as default parameter to the questionary.path() function.

How did you solve it?

We expand the type of default parameter to Path | str while also keeping its default value to be an empty string. Then we change the reference to this parameter on line 242 and we cast it to string using str(default). If default is of type Path, then we recieve the corresponding path as a string, if its type is str then nothing happens.

Checklist

• I have read the Contributor's Guide.
• I will check that all automated PR checks pass before the PR gets reviewed.