update package async (#207)

Author: pcardune

package.json

@@ -10,7 +10,7 @@
   ],
   "description": "handlebars loader module for webpack",
   "dependencies": {
-    "async": "~0.2.10",
+    "async": "^3.2.2",
     "fastparse": "^1.0.0",
     "loader-utils": "1.0.x",
     "object-assign": "^4.1.0"