Exclude tests in setup.py

[aldenrogers]

Proposed changes

This fixes #507 by specifying in setup.py that tests should not be packaged.

Types of changes

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

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• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
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• Any dependent changes have been merged and published in downstream modules

Further comments

Compare https://github.com/quiltdata/quilt/pull/2632/files for an example of a similar change elsewhere.

[CLAassistant]

All committers have signed the CLA.

[aldenrogers]

I'll need some time to confirm with my employer before signing the CLA

[jeongyoonlee]

LGTM. Thanks for the contribution!