[New Feature]: persistent test data on CircleCI

[LiangJYu]

Checked for duplicates

Yes - I've already checked

Alternatives considered

Yes - and alternatives don't suffice

Related problems

#46 requires downloading ~800MB of data of zenodo.com. Measures have been taken to prevent repeat downloads for local usage, but to my understanding nothing exists to prevent this from happening in CircleCI. Repeated downloading slows down test run time.

Describe the feature request

Could using CircleCI's artifact feature help address the repeated downloading of the same data by persisting the downloaded test data?

[vbrancat]

@LiangJYu, I believe we can close this issue.