Fix type hint for with_for_update() to support tuples of table classes

Fix type hint for with_for_update() to support tuples of table classes

Fixed typing issue where :meth:`.Select.with_for_update` would not support
lists of ORM entities in the :paramref:`.Select.with_for_update.of`
parameter. Pull request courtesy Shamil.

Fixes: #12730
Closes: #12988
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/12988
Pull-request-sha: 41a38bfe38d8b66da853012e7165cc0cacf7f28a

Change-Id: I61d60a4f4d2b16037da8d5f30e33f5d74fa47374
(cherry picked from commit a057c474bf84ccd0508b89aa5428f45c9a644ee3)