[BB-1105] circleci: switch to ubuntu:xenial
Created by: dupainaulevain
Because CircleCI jessie based images are no longer working and Xenial is what production uses, and it makes sense to test on the same distribution.
Created by: dupainaulevain
Because CircleCI jessie based images are no longer working and Xenial is what production uses, and it makes sense to test on the same distribution.