fix broken api

e621.py

@@ -137,7 +137,7 @@ class E621Post:
 class E621PostVersion:
     id: int
     post_id: int
-    tags: Optional[str]
+    tags: str
     updater_id: int
     updated_at: str
     rating: Rating
@@ -177,7 +177,7 @@ class E621:
         })).json()
         if 'success' in r:
             return []
-        return [E621PostVersion.from_dict(p) for p in r if p['version']]
+        return [E621PostVersion.from_dict(p) for p in r if p['tags']]
 
     async def get_tag_aliases(self, name: str) -> List[str]:
         data = (await self.client.get('/tag_aliases.json', params={'search[antecedent_name]': name})).json()