h5ad-to-arrow not building

[ilan-gold]

Travis output here: https://travis-ci.com/github/hubmapconsortium/portal-containers/builds/155569467

There seems to be an issue with conda being installed via pip:

ERROR: Could not find a version that satisfies the requirement conda==4.7.12 (from -r ./requirements-freeze.txt (line 6)) (from versions: 3.0.6, 3.5.0, 3.7.0, 3.17.0, 4.0.0, 4.0.1, 4.0.2, 4.0.3, 4.0.4, 4.0.5, 4.0.7, 4.0.8, 4.0.9, 4.1.2, 4.1.6, 4.2.6, 4.2.7, 4.3.13, 4.3.16)

ERROR: No matching distribution found for conda==4.7.12 (from -r ./requirements-freeze.txt (line 6))

The command '/bin/sh -c pip install  -r ./requirements-freeze.txt' returned a non-zero code: 1

The command "./test.sh" exited with 1.

[ilan-gold]

Pinning back to previous version seemed to help: https://travis-ci.com/github/hubmapconsortium/portal-containers/builds/155573314

The image is now continuumio/miniconda3:4.7.12