`invalid-name` type alias false-positive for union variables without assignment values

[yilei]

Bug description

# pylint: disable=missing-docstring
from typing import Union
x: Union[str, int]

Configuration

No response

Command used

pylint t.py

Pylint output

************* Module t
t.py:3:0: C0103: Type alias name "x" doesn't conform to predefined naming style (invalid-name)

Expected behavior

No output.

Pylint version

pylint 2.17.2
astroid 2.15.2
Python 3.11.1 (main, Jan 10 2023, 15:08:01) [Clang 14.0.0 (clang-1400.0.29.202)]

OS / Environment

No response

Additional dependencies

Similar to #8487. This is a bug found in #8537, let me send a separate PR first.