chore(package): update ember-source to version 3.13.4

Closes #58

Author: greenkeeper[bot]

package.json

@@ -49,7 +49,7 @@
     "ember-maybe-import-regenerator-for-testing": "^1.0.0",
     "ember-qunit": "^4.4.1",
     "ember-resolver": "^5.1.3",
-    "ember-source": "~3.10.0",
+    "ember-source": "~3.13.4",
     "ember-source-channel-url": "^2.0.1",
     "ember-try": "^1.2.1",
     "eslint-plugin-ember": "^6.2.0",