Support aarch64 architecture

I can confirm these modifications make Obsidian work on aarch64. I have these modifications in place on top of the official PKGBUILD since October 2024 and applied in on every new release.

Not touching the arch array, but just proposing subtle changes to make things work, according to https://lists.archlinux.org/archives/list/arch-dev-public@lists.archlinux.org/thread/LTJPVTU3QOYTDM7NNQIJPM63W2SDZNGF/

Thanks!