Exclude the tests from wheels.

[KOLANICH]

No description provided.

[lucaswiman]

This seems to be sensitive to how the wheel/dist tarball is actually built. Using python -m build (as suggested in this guide), the test files are included, but using python setup.py bdist_wheel, they aren't. But I've also seen a blog post suggesting you shouldn't invoke setup.py directly.

I haven't kept up to date on the many changes of python packaging, so it would be good to have a "recipe" (or eventually a script) to do releases. Could you please combine this PR with #217 and add a DEVELOPING.md (or .rst) file with a "Releases" section describing how to do a release? If I understand correctly, it would be:

• Tag a release with git tag -a VERSION -m 'VERSION' or something
• Some command to build the wheel and sdist, e.g. python setup.py bdist_wheel
• Upload command, e.g. twine upload dist/*