ci: install cpptrace dep for qs

It isn't in the Arch repos...

.github/actions/setup-arch/action.yml

@@ -28,6 +28,12 @@ runs:
       run: |
         useradd -m builder
         echo 'builder ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers
-        sudo -u builder git clone https://aur.archlinux.org/quickshell-git.git /home/builder/quickshell-git
-        cd /home/builder/quickshell-git
-        sudo -u builder makepkg -si --noconfirm
+
+        install_pkg() {
+          sudo -u builder git clone https://aur.archlinux.org/$1.git /home/builder/$1
+          cd /home/builder/$1
+          sudo -u builder makepkg -si --noconfirm
+        }
+
+        install_pkg cpptrace  # Dep for qs
+        install_pkg quickshell-git