subprojects: Limit clone depth to 1 in wrap files
This should save a bit of bandwidth when downloading subprojects.
See https://mesonbuild.com/Wrap-dependency-system-manual.html#specific-to-wrapgit and https://tecnocode.co.uk/2020/07/09/easily-speed-up-ci-by-reducing-download-size/.
Signed-off-by: Philip Withnall pwithnall@endlessos.org