Update version numbers

Update MANIFEST.in to exclude tests.

Update version number and conda recipe.

- Also drop Python 3.7 since it's no longer on conda-forge.

Release v0.4.0

Merge pull request #50 from EducationalTestingService/release/0.3.2

Release/0.3.2

Merge pull request #36 from EducationalTestingService/release/0.3.1

Release 0.3.1

update to meta.yaml

version 0.2.3