Upgrade Docker for multi-stage builds (v17.05+)

We'd like to use bitbucket pipelines, but we require the multistage build feature introduced in docker 17.05. Unfortunately the version reported in bitbucket pipeline is from the 1.12 series, which is now almost a year old.

Is there a way by which we can run a newer version of docker for our pipelines or is there a timeline for when bitbucket pipeline's version of docker will be updated to a more current one?