Add openstack-dev/sandbox to zuulv3.o.o
We need a project where we can tag (pre-)releases, add sandbox so we
can do just that.
- openstack-infra/openstack-zuul-roles
# After this point, sorting projects alphabetically will help
# merge conflicts
+ - openstack-dev/sandbox
- openstack-infra/nodepool
- openstack-infra/shade
- openstack-infra/zuul
