Merge pull request #7342 from BabylonJS/drigax/LoadDebugSerializerInPlayground

load babylon.serializers.js when using the debug playground page

Playground/debug.html

@@ -94,7 +94,7 @@
 
 
 
-    <script src="https://preview.babylonjs.com/serializers/babylonjs.serializers.min.js"></script>
+    <script src="https://preview.babylonjs.com/serializers/babylonjs.serializers.js"></script>
 
     <!-- Monaco -->
     <script src="node_modules/monaco-editor/dev/vs/loader.js"></script>