Disallowed typing in `linalg.vector_norm`

[lucascolley]

Spec:

ord: int | float | ~typing.Literal[inf, -inf] = 2

Stubs:

ord: Union[int, float, Literal[inf, -inf]] = 2

Literals docs

The following are provisionally disallowed for simplicity. We can consider allowing them in the future.

• Floats: e.g. Literal[3.14]. Representing Literals of infinity or NaN in a clean way is tricky; real-world APIs are unlikely to vary their behavior based on a float parameter.

A relevant issue: https://github.com/python/typing/issues/1160

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I don't know if anything can be done, and this was probably done deliberately, but useful to have an issue nonetheless.