feat: use numeric dtype for MatLike instead of generic

[VadimLevin]

closes #24803

cv2/typing/__init__.py:

import typing as _typing

if _typing.TYPE_CHECKING:
    NumPyArrayNumeric = numpy.ndarray[_typing.Any, numpy.dtype[numpy.integer[_typing.Any] | numpy.floating[_typing.Any]]]
else:
    NumPyArrayNumeric = numpy.ndarray

MatLike = _typing.Union[cv2.mat_wrapper.Mat, NumPyArrayNumeric]

Test file (test_numeric_ndarray.py) content:

import numpy as np
import cv2

mask = np.zeros((4, 4), dtype=np.uint8)
contours, hierarchy = cv2.findContours(mask, cv2.RETR_CCOMP, cv2.CHAIN_APPROX_TC89_KCOS)
contour = contours[0] * 2

pyproject.toml content

[tool.mypy]
strict = true
ignore_missing_imports = true
plugins = [
    "numpy.typing.mypy_plugin"
]

$ mypy test_numeric_ndarray.py
Success: no issues found in 1 source file

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