CI: upgrade actions/checkout to v3
CI: upgrade actions/checkout to v3

malloch/libmapper,libmapper/libmapper,libmapper/libmapper,libmapper/libmapper,malloch/libmapper,libmapper/libmapper,libmapper/libmapper,libmapper/libmapper,malloch/libmapper,malloch/libmapper,malloch/libmapper,malloch/libmapper