chore(package): update ember-source to version 3.8.0

Closes #209

Author: greenkeeper[bot]

package.json

@@ -40,7 +40,7 @@
   "devDependencies": {
     "chai": "^4.1.0",
     "chai-as-promised": "^7.1.1",
-    "ember-source": "3.2.0",
+    "ember-source": "3.8.0",
     "eslint": "^5.10.0",
     "eslint-plugin-chai-expect": "^2.0.1",
     "eslint-plugin-mocha": "^5.2.0",