Include test files in packages properly

Conda forge is failing because some files needed for testing aren't included in the package: https://dev.azure.com/conda-forge/feedstock-builds/_build/results?buildId=1156761&view=logs&j=7b6f2c87-f3a7-5133-8d84-7c03a75d9dfc&t=9eb77fd2-8ddd-5444-8fc0-71cb28dcb736

These need to be included in the next version to get conda forge to work properly.