fix

main.py

@@ -113,7 +113,7 @@ def authenticate_user(fake_db, username: str, password: str):
         return False
     return user
 
-def create_access_token(data: dict, expires_delta: timedelta | None = None):
+def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
     to_encode = data.copy()
     if expires_delta:
         expire = datetime.now(timezone.utc) + expires_delta