Pin the version of git used in Darwin CI

Followup to #24055 (closed).

On Darwin, git comes from the system and isn't pinned. Some versions of git seemed to have a bug that was the root cause of #24055 (closed). The bug was present in 2.40.1, but absent in 2.42.0.

Darwin CI should use a pinned, working version of git to prevent future surprises.

Edited Oct 19, 2023 by Bryan R

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information