Use a TypedDict for turtle._PenState

[kbaikov]

All is taken from the docstring of the pen function: https://github.com/python/cpython/blob/d5a08f0ecb31dddd5c2c5d8f4121f22d95913434/Lib/turtle.py#L2351

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[Akuli]

Looks good. Thanks!

[Akuli]

These are always returned as strings. For example:

>>> import turtle
>>> turtle.pen(pencolor=(1,0,0))
>>> turtle.pen()
{'shown': True, 'pendown': True, 'pencolor': '#ff0000', ...

However, using str here is not any better, because it is not wrong to have tuples in pen state dicts:

>>> p = turtle.pen().copy()
>>> p['pencolor'] = (0,1,0)
>>> turtle.pen(p)
>>> turtle.pen()['pencolor']
'#00ff00'