Disallow kwargs from genericalias __new__.

[DimitrisJim]

@Snowapril a review would be great if you could.

[youknowone]

it looks original code is still disallowing kwargs. is it changing error message?

[DimitrisJim]

@youknowone Oh right, yeah, basically that, bad naming.

[Snowapril]

Good! Some incompatibility now become correct.

rustpython

>>>>> GenericAlias()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Expected at least 0 arguments (0 given)
>>>>> kwargs = {"origin":int, "arguments":int}
>>>>> GenericAlias(**kwargs)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: GenericAlias() takes no keywords

python

>>> GenericAlias()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: GenericAlias expected 2 arguments, got 0
>>> kwargs = {"origin":int, "arguments":int}
>>> GenericAlias(**kwargs)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: GenericAlias() takes no keyword arguments

[Snowapril]

Totally looks good to me 😊

[youknowone]

The message "takes no keyword arguments" is commonly repeated. I wish we have a way to handle this better.