fix(package): update ember-cli-htmlbars to version 5.1.0

Closes #218

Author: greenkeeper[bot]

package.json

@@ -24,7 +24,7 @@
   "dependencies": {
     "ember-auto-import": "^1.5.3",
     "ember-cli-babel": "^7.13.0",
-    "ember-cli-htmlbars": "^4.2.0",
+    "ember-cli-htmlbars": "^5.1.0",
     "microstates": "^0.15.1"
   },
   "devDependencies": {