chore(deps): update yarn.lock, add missing deps

Author: buschtoens

package.json

@@ -37,6 +37,7 @@
   "devDependencies": {
     "@clark/eslint-config-node": "^2.0.0",
     "@ember/optional-features": "^2.0.0",
+    "@ember/test-helpers": "^2.1.4",
     "broccoli-asset-rev": "^3.0.0",
     "ember-cli": "~3.24.0",
     "ember-cli-babel": "^7.23.1",
@@ -57,6 +58,7 @@
     "ember-try": "^1.4.0",
     "eslint": "^7.19.0",
     "loader.js": "^4.2.3",
+    "qunit": "^2.14.0",
     "qunit-dom": "^1.6.0"
   },
   "peerDependencies": {