ci: prevent mergify conflict message for dependabot PRs
ci: prevent mergify conflict message for dependabot PRs

There is no use in having Mergify posting messages to Dependabot and
asking for resolving of merge conflicts. Dependabot will try to do that
automatically, and posts a message when some other action is needed.

Signed-off-by: Niels de Vos <7bda0c0ee7f47171cc808e9e60292cbc5d8140dd@redhat.com>

ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi