New review comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/25826#discussion_r511525492

Comment:
The makefile inlcuded in the tarball uses `pytest` to run the `test` target. Add `python3-pytest` to `checkdepends` and replace `./selftest.py` with `python3 -m pytest`. This will run more thorough tests. You can keep the subshell trick to set `PYTHONPATH`, which will still be required.