Update app.py

app.py

@@ -619,7 +619,7 @@ def reset_chat(histories, memory_state, flags_state):
 
 def load_css(path="style.css") -> str:
     try:
-        with open(path, "r", encoding:"utf-8") as f:
+        with open(path, "r", encoding="utf-8") as f:
             return f.read()
     except FileNotFounError:
         return ""