bpo-44632: Fix support of TypeVar in the union type (GH-27139) (GH-27143)

int | TypeVar('T') returns now an instance of types.Union
instead of typing.Union.
(cherry picked from commit a158b20019b50e3ece6e4743ec4e6ae8d818b690)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>