remove dead instance

Author: hyperdefined

backend/instances

@@ -12,5 +12,4 @@ cobalt-backend.canine.tools,cobalt.canine.tools,https
 cobalt-api.kwiatekmiki.com,cobalt.kwiatekmiki.com,https
 subito-c.meowing.de,cobalt.meowing.de,https
 nuko-c.meowing.de,cobalt.meowing.de,https
-api.cobalt.blackcat.sweeux.org,cobalt.blackcat.sweeux.org,https
 cobalt-api.clxxped.lol,cobalt.clxxped.lol,https