ssllabs api endpoint has changed

https://api.ssllabs.com/api/v2/ seems to be dead and has been replaced by https://api.ssllabs.com/api/v3/ . See https://github.com/ssllabs/ssllabs-scan/blob/master/ssllabs-api-docs-v3.md

`check-ssl-qualys.rb --api-url https://api.ssllabs.com/api/v3/ ` is working for me, so I suspect that updating the api url is sufficient.
