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

Author: greenkeeper[bot]

package.json

@@ -63,7 +63,7 @@
     "ember-maybe-import-regenerator-for-testing": "^1.0.0",
     "ember-resolver": "^5.0.1",
     "ember-sinon": "^2.2.0",
-    "ember-source": "~3.4.0",
+    "ember-source": "~3.8.0",
     "eslint-plugin-ember": "^6.0.0",
     "eslint-plugin-node": "^7.0.1",
     "glob": "^7.1.3",