fix(theme-chooser): use `env` in shebang (#12720)

tools/theme_chooser.sh

@@ -1,4 +1,4 @@
-#!/bin/zsh
+#!/usr/bin/env zsh
 
 # Zsh Theme Chooser by fox (fox91 at anche dot no)
 # This program is free software. It comes without any warranty, to