[3.13] Replace "ordered arguments" with "positional arguments" in `unittest.mock` documentation (GH-137552) (GH-137554)

Replace "ordered arguments" with "positional arguments" in `unittest.mock` documentation (GH-137552)
(cherry picked from commit 64ee1babfb971ddbc00fd8711cccebfbddf6e4ee)

Co-authored-by: Tom Forbes <tom@tomforb.es>