fix(genpass): add compatibility for macOS paste command

"paste" on macOS requires a '-' to signify that the standard input is used.
Without the '-' character, the command errors out.

plugins/genpass/genpass.plugin.zsh

@@ -101,6 +101,6 @@ genpass-xkcd() {
 
   for i in {1..$num}; do
     printf "$n-"
-    printf "$dict" | shuf -n "$n" | paste -sd '-'
+    printf "$dict" | shuf -n "$n" | paste -sd '-' -
   done
 }