fix(script): Check severity against actaual severity value (#1)

Instead of checking against hard-coded string 'imp'

pacman-zfs-snapshot.sh

@@ -127,7 +127,7 @@ function trim_globally_snappable_datasets () {
 }
 
 function write_pkg_list_oneline () {
-    if [[ "${severity}" == 'imp' ]]; then
+    if [[ "${severity}" == "${snaps_important_suffix}" ]]; then
         for pkg in "${important_pkgs_in_transaction[@]}"; do
             if [[ "${unabridged_pkg_list_oneline}" ]]; then
                 unabridged_pkg_list_oneline="${unabridged_pkg_list_oneline}${pkg_separator}${pkg}"