fix(lib): use -N syntax in head and tail to support Solaris (#6391)

Closes #6391

Co-authored-by: Sergey Mashkov <cy6erGn0m@gmail.com>

lib/functions.zsh

@@ -1,7 +1,7 @@
 function zsh_stats() {
   fc -l 1 \
     | awk '{ CMD[$2]++; count++; } END { for (a in CMD) print CMD[a] " " CMD[a]*100/count "% " a }' \
-    | grep -v "./" | sort -nr | head -n20 | column -c3 -s " " -t | nl
+    | grep -v "./" | sort -nr | head -20 | column -c3 -s " " -t | nl
 }
 
 function uninstall_oh_my_zsh() {