title: SSL verification error in python
body: <p>I am using the slackClient library to create a slack bot but I get ssl verification failed error when I use api.call() method of slack client. I was facing the same issue while using pip install but that got resolved by using --trusted-host. Is there some configuration in python required to access machine certs? </p>
  
  <p>I have already imported the root cert into windows certificate manager and I am able to open the URL in browser securely without encountering message like "There is a problem with this website’s security certificate". 
  I do not want to disable the SSL verification</p>
  
  <p>I referred to the answers given at 
  <a href="https://stackoverflow.com/questions/45408850/ssl-certificate-verify-failed-certificate-verify-failed">SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed</a></p>
  
  <p>but slack client library calls urllib3 internally and I am not able to specify ca-file for it.</p>
  
  <p>Is there a way to resolve this issue and configure python to use machine certs directly?</p>