개발 환경에서는 문제가 없다가 실서버에서 돌리니 인증서 오류가 발생 했다. Failed to send a request to Slack API server: Failed to send a request to Slack API server: Traceback (most recent call last): File "/home/apps/python3.7/lib/python3.7/urllib/request.py", line 1317, in do_open encode_chunked=req.has_header('Transfer-encoding')) File "/home/apps/python3.7/lib/python3.7/http/client.py", line 1229, in request self._send_req..