Update to latest master

This release fixes the mirrorlist generator, removes some old css and
upgrades django to 1.11.12.

roles/archweb/defaults/main.yml

@@ -7,7 +7,7 @@ archweb_domains_redirects:
         'dev.archlinux.org': '/'
         'packages.archlinux.org': '/packages$1'
 archweb_repository: 'https://github.com/archlinux/archweb.git'
-archweb_version: dad8fa4a842d6e140cb6c31799d01b04bd063b26
+archweb_version: 7c31264cfac431facd0cd81d026e9c72084488b0
 archweb_site: true
 archweb_mirrorcheck: false
 archweb_mirrorresolv: false