Fix the zuul-coverage job (test-requires update).

The zuul-coverage job depends on the coverage tool. Add it to
tools/test-requires list.

Change-Id: I4c5609f7992dd6dae649f5c059a69bb06b021831
Reviewed-on: https://review.openstack.org/10684
Approved: James E. Blair <corvus@inaugust.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins
1 file changed