Warning about target mode

[ctapmex]

when you run octodns with selectel, we get a warning

2025-01-25T15:04:36  [125633851420800] INFO  SelectelProvider[selectel] plan: desired=example.com.
2025-01-25T15:04:38  [125633851420800] INFO  SelectelProvider[selectel] populate: found 9 records
2025-01-25T15:04:38  [125633851420800] WARNING SelectelProvider[selectel] Provider selectel used in target mode did not return exists
2025-01-25T15:04:38  [125633851420800] INFO  SelectelProvider[selectel] root NS record in existing, but not supported or not configured; ignoring it
2025-01-25T15:04:38  [125633851420800] INFO  SelectelProvider[selectel] plan:   Creates=1, Updates=0, Deletes=0, Existing Records=8

add these lines after

exists = zone.name in self._zones
return exists

[ross]

PRs welcomed.