[3.12] gh-105340: include hidden fast-locals in locals() (GH-105715) (#106470)

gh-105340: include hidden fast-locals in locals() (GH-105715)

* gh-105340: include hidden fast-locals in locals()
(cherry picked from commit 104d7b760fed18055e4f04e5da3ca619e28bfc81)

Co-authored-by: Carl Meyer <carl@oddbird.net>