chore(.github): add storage-dpe group as owner
This will allow anyone on the storage-dpe team to approve PRs for
storage.
/pubsub/ @googleapis/api-pubsub @googleapis/yoshi-go-admins
/pubsublite/ @googleapis/api-pubsub @googleapis/yoshi-go-admins
/spanner/ @skuruppu @googleapis/yoshi-go-admins
-/storage/ @tritone @googleapis/yoshi-go-admins
+/storage/ @googleapis/storage-dpe @googleapis/yoshi-go-admins
/errorreporting/ @googleapis/api-logging @googleapis/yoshi-go-admins
/logging/ @googleapis/api-logging @googleapis/yoshi-go-admins
/profiler/ @googleapis/api-profiler @googleapis/yoshi-go-admins
