Update doc strings type hints

[angusgoody]

Is your feature request related to a problem? Please describe.
In gnupg.py a few of the doc strings type hint kwargs as kwargs (dict) this confuses some IDE's as it expects the parameter passed to the function to be of type dict. However when using the function kwargs are passed as named pairs so the IDE throws a warning

Describe the solution you'd like
To update the doc strings from kwargs (dict) to **kwargs to remove warnings in IDE

Additional context