Fix: bpy_prop_array.__getitem__(slice) to return tuple

[Andrej730]

See example:

from typing import assert_type
import bpy

obj = bpy.context.active_object
assert obj

# <class 'bpy_prop_array'>
print(type(obj.color))
# (1.0, 1.0, 1.0, 1.0)
print(obj.color[:])

# "assert_type" mismatch: expected "tuple[float, ...]" but received "list[float]"
assert_type(obj.color[:], tuple[float, ...])