feat(package): bump testdouble

Author: alexblom

package.json

@@ -29,7 +29,7 @@
     "broccoli-funnel": "^1.2.0",
     "broccoli-merge-trees": "^2.0.0",
     "ember-cli-babel": "^6.6.0",
-    "testdouble": "^2.1.2"
+    "testdouble": "^3.5.2"
   },
   "devDependencies": {
     "broccoli-asset-rev": "^2.4.5",