Copy the pygal.js file into the pyodide/packages/ directory

I think I have finished porting pygal.js from a Skulpt module to a plain
JavaScript ES6 module which is now supported in Pyodide.

More context:
trinketapp/pygal.js#12

Author: tuzz

pyodide/index.html

@@ -42,7 +42,7 @@
     <div id="visual" style="width: fit-content;"></div>
 
     <script type="module">
-      import * as pygal from "../../pygal.js/pygal.js";
+      import * as pygal from "./packages/pygal.js";
 
       const runButton = document.getElementById("run");
       const input = document.getElementById("input");