Update packaging for Python 3-only distribution (#137)
Update packaging for Python 3-only distribution (#137)

Remove universal wheel flag from setup.cfg bdist_wheel config,
because universal wheels must support both Python 2 and 3.[1]

(We can and should still distribute as a non-universal "pure
Python" bdist_wheel because this package does not contain any
compiled platform code.)

[1]: https://packaging.python.org/guides/distributing-packages-using-setuptools/#universal-wheels
syrusakbary/snapshottest