Make CNAME '@' values absolute

If a CNAME has an '@' value, octoDNS will complain about an invalid
record because the value is missing a trailing dot. Since NetBox DNS
doesn't support adding a trailing dot after '@', this value must be
absolute, regardless of the configuration of the 'make_absolute'
setting.

src/octodns_netbox_dns/__init__.py

@@ -250,7 +250,11 @@ def _format_nb_records(self, zone: octodns.zone.Zone) -> list[dict[str, Any]]:
         )
         for nb_record in nb_records:
             rcd_name: str = "" if nb_record.name == "@" else nb_record.name
-            rcd_value: str = nb_record.zone.name if nb_record.value == "@" else nb_record.value
+            rcd_value: str = (
+                self._make_absolute(nb_record.zone.name, True)
+                if nb_record.value == "@"
+                else nb_record.value
+            )
             rcd_type: str = nb_record.type
             rcd_ttl: int = nb_record.ttl or nb_zone.default_ttl
             if nb_record.type == "NS":