Fix errors detected by Ruff (#3918)

### What problem does this PR solve?

Fix errors detected by Ruff

### Type of change

- [x] Refactoring

api/apps/llm_app.py

@@ -351,8 +351,10 @@ def list_app():
 
         llm_set = set([m["llm_name"] + "@" + m["fid"] for m in llms])
         for o in objs:
-            if not o.api_key: continue
-            if o.llm_name + "@" + o.llm_factory in llm_set: continue
+            if not o.api_key:
+                continue
+            if o.llm_name + "@" + o.llm_factory in llm_set:
+                continue
             llms.append({"llm_name": o.llm_name, "model_type": o.model_type, "fid": o.llm_factory, "available": True})
 
         res = {}