Mandatory upgrade to v1.8.0 unavailable in Arch Linux AUR

Since some v1.8.0 users are getting trade errors when transacting with users on earlier versions, and the upgrade to v1.8.0 is mandatory, the Arch Linux AUR probably needs to be updated ASAP to avoid further trade problems escalating.

Relevant links:
https://aur.archlinux.org/packages/bisq/