require zsh >= 5.4 for state dumps

internal/p10k.zsh

@@ -3358,7 +3358,7 @@ _p9k_save_status() {
 }
 
 function _p9k_dump_state() {
-  is-at-least 5.3 || return
+  is-at-least 5.4 || return  # `typeset -g` doesn't roundtrip in zsh prior to 5.4.
   local dir=${__p9k_dump_file:h}
   [[ -d $dir ]] || mkdir -pm 0700 $dir || return
   [[ -w $dir && -z $dir(#qNR) ]] || return