[pynest] Add type hints.

[babsey]

When reviewing pynest, I registered that the arguments are not typed.

As example:

def SetDefaults(model, params, val=None):
....

According to several links:

• Typing
• PEP 484

I would suggest to add type hints in pynest like this:

def SetDefaults(model: str, params: dict | str, val: Any=None):

Lets hear your thoughts on this suggested feature.