Support PKGBUILD files (Arch Linux)

[orhun]

PKGBUILD files are bash scripts that are being used in Arch Linux's package management and they contain the build instructions for a package. See the PKGBUILD of tokei as an example.

Now, these files are not languages per se, but we use Git for repository management (as you can see from the GitLab link) and I thought it would be a good idea to recognize a Arch Linux package repository if there is a PKGBUILD in the current directory.

It can either show "PKGBUILD" or "bash" as the language.

Edit: Just saw that this was implemented in #972 and there is #888, however this doesn't work for me:

onefetch on  main
>_ orhun ζ tokei
===============================================================================
 Language            Files        Lines         Code     Comments       Blanks
===============================================================================
===============================================================================
 Total                   0            0            0            0            0
===============================================================================