Check version of git or reimplement git restore

[renatav]

git restore was introduced since git v2.23, IIUC. We currently don't seem to have a way to let the user know that the installed git is incompatible with currently installed taf.

E.g. user has outdated git installed (v2.21) and tries to run a taf API command. This seems like it should probably be a separate issue? What we could possibly do is something along the lines of have taf cli emit warning if outdated git is installed?