Use latest A-Frame build from CDN

in particular, to get aframevr/aframe#5415

Author: Antonio Pisano

index.html

@@ -5,7 +5,7 @@
     <title>A-Painter</title>
     <link rel="icon" href="img/icon-256.png">
     <meta name="description" content="Paint in VR in your browser. Powered by A-Frame.">
-    <script src="vendor/aframe-master.min.js"></script>
+    <script src="https://cdn.jsdelivr.net/gh/aframevr/aframe@830c2567bbbb82ff40a565932b038529df348788/dist/aframe-master.min.js"></script>
     <script src="vendor/aframe-input-mapping-component.js"></script>
     <script src="build.js"></script>
     <script src="https://cdn.jsdelivr.net/npm/clipboard@1.5.12/dist/clipboard.min.js"></script>