This is used for git submodule update --remote for example as well as by
the CI (in the future) to know where to fetch from when the submodule
sha1 is bumped.

Change-Id: I4a544627b836488f00e1ca60d07d3ce69c6ce4b7
Reviewed-by: Paolo Angelelli <paolo.angelelli@qt.io>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>