add 'trending' option to sorting criteria in find_similar_models function

main.py

@@ -394,7 +394,7 @@ async def find_similar_models(
     model_id: str,
     k: int = Query(default=5, ge=1, le=100),
     sort_by: str = Query(
-        default="similarity", enum=["similarity", "likes", "downloads"]
+        default="similarity", enum=["similarity", "likes", "downloads", "trending"]
     ),
     min_likes: int = Query(default=0, ge=0),
     min_downloads: int = Query(default=0, ge=0),