MAINT: Timestamp nightly wheel filenames

[tylerjereddy]

Based on discussion with @mattip in #74, downstream projects using pip to pull in our wheels from the nightly (weekly) anaconda.org repo appear to need dates stamped right into filenames, presumably because pip is not scraping timestamp metadata directly from the uploaded files.

So it just kind of arbitrarily sorts by hash alphanumerically, which is bad.

While I'd prefer if there were a simple pip install flag of some sort that "just worked" for pulling in the latest based on metadata, I'll open this issue to try to get done soon-ish.

At least for us, we only need to worry about Travis--we haven't done nightlies for Windows/Appveyor in recent history AFAIK.

[bashtage]

I don't think you have to timestamp. You could also use the structure

scipy-1.5.0.dev0+NUMBER_OF_COMMITS_AFTER_dev0.g6fd3052-cp38-cp38-macosx_10_9_x86_64.whl

[tylerjereddy]

Following the merging of the cross-linked PR above--I should check mid-week after the Tuesday "nightly" upload to see if the wheels are properly named for downstream pip download purposes.

[tylerjereddy]

The timestamping appears to have worked as intended for the weekly uploads last Tuesday: https://anaconda.org/scipy-wheels-nightly/scipy/files

I've also manually purged the older weekly wheel uploads, with incorrect file naming, to prevent interference with automated downloads from downstream projects using pip in CI, etc.

So, I'll close this issue. @bashtage -- feel free to open an issue/ping me if statsmodels or other projects are having issues with our weekly wheels.