[3.10] bpo-44490: Add __parameters__ and __getitem__ to types.Union (GH-26980) (GH-27207)

Co-authored-by: Ken Jin <28750310+Fidget-Spinner@users.noreply.github.com>
Co-authored-by: Guido van Rossum <gvanrossum@gmail.com>.
(cherry picked from commit c45fa1a5d9b419cf13ad4b5a7cb453956495b83e)

Co-authored-by: Yurii Karabas <1998uriyyo@gmail.com>
Co-authored-by: Ken Jin <28750310+Fidget-Spinner@users.noreply.github.com>
5 files changed