text: Title: Why we don't use certifi root certificates by default?
  Body: Hey there,
  
  Today my colleauge step into the problem with ceritificate that time to time appears with other people who use your client.
  You can read about this problem more here:
  https://stackoverflow.com/questions/59808346/python-3-slack-client-ssl-sslcertverificationerror
  
  As I see the problem that people have some problem with root certificates on their machine.
  Python always had a problem with root certificatates and to solve this problem people started to use the project certifi.
  
  For example you can find usage of this project in the kinda popular library `requests`
  https://github.com/psf/requests/blob/main/src/requests/utils.py#L63
  https://github.com/psf/requests/blob/main/src/requests/adapters.py#L294
  
  Do you have any reason to don't use library certifi as requests library uses?
  
  I think it would simplify of using your library everywhere.
  
  