chore: add antergos-pkgs repo to pacman.conf and squashfs-tools for Calamares unpackfs

- airootfs/etc/pacman.conf: enable antergos-pkgs repo for installing
  branded packages from GitHub Pages
- packages.x86_64: add squashfs-tools needed by Calamares unpackfs
  module

airootfs/etc/pacman.conf

@@ -93,8 +93,7 @@ Include = /etc/pacman.d/mirrorlist
 [multilib]
 Include = /etc/pacman.d/mirrorlist
 
-# An example of a custom package repository.  See the pacman manpage for
-# tips on creating your own repositories.
-#[custom]
-#SigLevel = Optional TrustAll
-#Server = file:///home/custompkgs
+[antergos-pkgs]
+SigLevel = Optional TrustAll
+Server = https://Antergos-NeXT.github.io/antergos-packages/$repo/os/$arch
+Server = https://Antergos-NeXT.github.io/antergos-packages

packages.x86_64

@@ -273,5 +273,6 @@ yay
 cnchi
 calamares
 calamares-branding-antergos-next
+squashfs-tools
 mpv
 antergos-next-memes