Fixes the PROJECT_GIT_COMMIT_HASH not getting set in Github builds.

Previously, the step that should get the short ref using git failed:

fatal: detected dubious ownership in repository at '/__w/InfiniTime/InfiniTime'
To add an exception for this directory, call:

	git config --global --add safe.directory /__w/InfiniTime/InfiniTime

The checkout action is supposed to do that already, but for some reason it's not working:

Adding repository directory to the temporary git global config as a safe directory
/usr/bin/git config --global --add safe.directory /__w/InfiniTime/InfiniTime

It looks like this is an issue more people are facing, but for some reason the issue is closed: actions/checkout#1048

The proposed fix of setting the user wasn't working, so I'm just manually adding the cloned repository as safe.