PyPI prerelease version badge

:clipboard: **Description**

I just published a prerelease of tinyobjloader:

https://pypi.org/project/tinyobjloader/#history

As far as I can tell, there isn't a badge for displaying the latest prerelease version.

It looks like if there are _only_ prereleases, they do show correctly, e.g.

https://img.shields.io/pypi/v/black

:link: **Data**

It looks like the data source we use now includes both of the releases for this project, 0.1 and 2.0.0rc5.

https://pypi.org/pypi/tinyobjloader/json

:microphone: **Motivation**

It's common for projects to run prereleases for a long time, and it's useful to show users the latest published prerelease.

Start with the existing PyPI version badge endpoint, such as https://img.shields.io/pypi/v/black, and compare its data with the PyPI JSON endpoint shown for tinyobjloader. Trace how the endpoint selects versions; done means the latest published prerelease is displayed when the project also has a stable release.

Written by the indexing model from the issue text.