Apply arch build updates

Remove generated debug package, add python for substrate
build configuration.

.ci/helpers/archlinux-setup

@@ -77,5 +77,5 @@ sleep 2
 
 # Install required tools
 debug "installing build tools"
-lxc exec "${ctn_name}" -- pacman -Sy --noconfirm curl base-devel unzip zip ||
+lxc exec "${ctn_name}" -- pacman -Sy --noconfirm curl base-devel unzip zip python ||
     failure "Could not install required build tools"

package/build-archlinux

@@ -82,6 +82,9 @@ else
     makepkg --syncdeps --force --noconfirm || exit
 fi
 
+# Remove the debug package if it exists
+rm -f ./*-debug-*.zst
+
 # Move the package to the destination path
 mv ./*.zst "${output_path}" || exit