feat: add checksum to PKGBUILD

[harogaston]

I believe this should work to resolve #154 though I don't know how to test it locally. Uses https://github.com/marketplace/actions/publish-aur-package

[WillPower3309]

Hope you don't mind me requesting your review Erik! You have a lot more packaging experience than I

[ErikReider]

Not sure but I think that we'd need to update our secrets to match the ones required for the new action?

We'd also need to update the PKGBUILD in our repo for this to work. An example would be https://github.com/sane-fmt/sane-fmt/blob/c07ce4f09c0b8dfa902d28753ebb3800268183f5/template/sane-fmt-bin/PKGBUILD which also uses this action

[harogaston]

Thank you for having a look at it! I repeat that I am not very proficient regarding packaging. Though I could not understand why would there be needed any changes to secrets since this affects only the checksum. And also didn't quite get why PKGBUILD requires any changes, I believe the checksum will be added by updpkgsums.

Sorry if I am completely in the wrong here. Just trying to explain why I did what I did and nothing else but I am not very knowledgeable on this topics so feel free to use it or discard it if it is very far off.

Cheers!

[ErikReider]

We should move this to https://github.com/wlrfx/aur-packages