consider wheels

[Kriechi]

Many pypi packages only uploaded wheels, which poet doesn't consider.
This PR makes a small change to also accept wheels as artifact.

fixes #29

[tdsmith]

Can you give an example of a package that doesn't distribute an sdist? I don't think there are "many".

[tdsmith]

Homebrew-pypi-poet must not consider wheels with binary content; this should do tag matching on the filename to make sure it's a pure python wheel.

[tdsmith]

This isn't sufficient to resolve #29; some packages have entries on pypi but no uploaded distributions.

[Kriechi]

I'm one of the @mitmproxy maintainers, and we only ship wheels, because otherwise we run into problems with Python2 installations.

So I know of mitmproxy and one of our dependencies: construct.

[jbarlow83]

Python wheels should be the first choice and sdist should be the fallback.

Why not consider macOS binary wheels? People regularly install Homebrew and pip binaries.

[tdsmith]

Why not consider macOS binary wheels?

Homebrew policy (and therefore poet's policy) is to build from source.

Pure-python wheels are technically a distribution format and not a source format but the distinction feels less important and it might simplify things at some future point where setuptools is less dominant so I feel less strongly about it.