fix(deps): @ember/test-helpers: ^2.9.3 || ^3.0.0 || ^4.0.0

#832 (comment)

Author: buschtoens

ember-link/package.json

@@ -53,7 +53,7 @@
     "@glimmer/env": "^0.1.7"
   },
   "peerDependencies": {
-    "@ember/test-helpers": "^4.0.0",
+    "@ember/test-helpers": "^2.9.3 || ^3.0.0 || ^4.0.0",
     "@glimmer/tracking": "^1.1.2"
   },
   "devDependencies": {