Simple misname fix in world.geocache.visit

- Once again failed to name `com.atproto.repo.strongRef` properly

lexicon/world.geocache.visit.json

···
       "type": "object",
       "required": ["record"],
       "properties": {
-        "record": { "type": "ref", "ref": "com.atproto.ref.strongRef" }
+        "record": { "type": "ref", "ref": "com.atproto.repo.strongRef" }
       }
     },
     "image": {