Update app.py

app.py

@@ -6,11 +6,14 @@ import requests
 from io import BytesIO
 import os
 
+from typing import Optional
+
+
 app = FastAPI()
 
 class WelcomeRequest(BaseModel):
     username: str
-    avatar_url: str | None = None
+    avatar_url: Optional[str] = None
 
 def load_font(size: int = 60) -> ImageFont.FreeTypeFont:
     font_paths = [