CI: Sauce Connect randomly fails so try twice

Twice now I've seen Sauce Connect fail with the unhelpful message:

    Error: failed to bring up tunnel VM.

https://circle-artifacts.com/gh/mathquill/mathquill/192/artifacts/0/tmp/circle-artifacts.nHNHuWv/stdout_mkdir_13099.txt
  from https://circleci.com/gh/mathquill/mathquill/192
https://circle-artifacts.com/gh/laughinghan/mathquill/7/artifacts/0/tmp/circle-artifacts.aLi3FQ1/stdout_mkdir_10411.txt
  from https://circleci.com/gh/laughinghan/mathquill/7

Both of which succeeded on a rebuild without changing anything.
1 file changed