mathutils Color, Euler should have the __getitem__() method

[JonathanPlasse]

The following code is valid

from mathutils import Color, Euler

Color()[0]
Euler()[0]

This is the following code.

class Color:
    def __getitem__(self, key: int) -> float:
        ...


class Euler:
    def __getitem__(self, key: int) -> float:
        ...