TypeError: unsupported operand type(s) for +: 'type' and 'str'

• Python Version: 3.9.7
• aliyunsdkcore Version: 2.13.35
• API: UpdateDomainRecordRequest

TypeError: unsupported operand type(s) for +: 'type' and 'str'

Stack:

Traceback (most recent call last):
  File "c:\Codes\Web\ddns\ddns.py", line 38, in <module>
    response = client.do_action_with_exception(request)
  File "C:\Program Files\Python39\lib\site-packages\aliyunsdkcore\client.py", line 498, in do_action_with_exception
    status, headers, body, exception = self._implementation_of_do_action(acs_request)
  File "C:\Program Files\Python39\lib\site-packages\aliyunsdkcore\client.py", line 333, in _implementation_of_do_action
    return self._handle_retry_and_timeout(endpoint, request, signer)
  File "C:\Program Files\Python39\lib\site-packages\aliyunsdkcore\client.py", line 401, in _handle_retry_and_timeout
    status, headers, body, exception = self._handle_single_request(endpoint,     
  File "C:\Program Files\Python39\lib\site-packages\aliyunsdkcore\client.py", line 423, in _handle_single_request
    http_response = self._make_http_response(endpoint, request, read_timeout, connect_timeout,
  File "C:\Program Files\Python39\lib\site-packages\aliyunsdkcore\client.py", line 286, in _make_http_response
    header, url = signer.sign(self._region_id, request)
  File "C:\Program Files\Python39\lib\site-packages\aliyunsdkcore\auth\signers\access_key_signer.py", line 35, in sign
    url = request.get_url(region_id, cred.access_key_id, cred.access_key_secret)
  File "C:\Program Files\Python39\lib\site-packages\aliyunsdkcore\request.py", line 324, in get_url     
    url, string_to_sign = rpc_signer.get_signed_url(
  File "C:\Program Files\Python39\lib\site-packages\aliyunsdkcore\auth\composer\rpc_signature_composer.py", line 76, in get_signed_url
    signature = __get_signature(string_to_sign, secret, signer)
  File "C:\Program Files\Python39\lib\site-packages\aliyunsdkcore\auth\composer\rpc_signature_composer.py", line 68, in __get_signature
    return signer.get_sign_string(string_to_sign, secret + '&')
TypeError: unsupported operand type(s) for +: 'type' and 'str'

Start with aliyunsdkcore/auth/composer/rpc_signature_composer.py at __get_signature and trace how the signer reaches it from auth/signers/access_key_signer.py and request.py. Reproduce the UpdateDomainRecordRequest case on Python 3.9.7 with aliyunsdkcore 2.13.35; done means the reported TypeError no longer occurs.