def get_auth_info(self, url: str, username: str | None) -> tuple[str, str] | None:
        """Return the password for the given url and username.
        The username can be None.
        """
        if self.provider is None or not self.enabled:
            return None
        try:
            return self.provider.get_auth_info(url, username)
        except Exception:
            self.enabled = False
            return None
Return the password for the given url and username.
        The username can be None.
        
src/pdm/models/auth.py