Automate AUR updates

[Eeems]

https://aur.archlinux.org/packages/python-ext4

Example workflow: https://github.com/mxmlnkn/rapidgzip/blob/6d07da8a0ffe988cf9e1c4c4d04e52a7a6d6212f/.github/workflows/wheels-rapidgzip.yml#L152

• sha256sums instead of md5sums
• Remove tests as they were done before being pushed to pypi and not meant to be run outside of full source
• Remove commented out docs
• Download wheel from pypi instead of building wheel from srcdist