There's a closed pull request on the void-packages repository

python-mistune: update to 2.0.0a5.
https://github.com/void-linux/void-packages/pull/24798

Description:
Needed for packaging `md2gemini` (forthcoming). `md2gemini` needs a later version than 0.8.4, which is what's currently available on PyPi, so i'm using the latest release tagged in the `mistune` GH repo. `./xbps-src pkg` completes successfully. i've also fixed xlint errors, including changing the short_desc.

Finally, i've taken this opportunity to remove the `archs=noarch` lines.