fix: move ember-test-selectors to dependencies

This makes sure that the test selectors are not part of prod builds.
https://github.com/mainmatter/ember-test-selectors?tab=readme-ov-file#usage-in-ember-addons

Author: czosel

package.json

@@ -60,6 +60,7 @@
     "ember-modifier": "^4.1.0",
     "ember-promise-helpers": "^2.0.0",
     "ember-simple-auth-oidc": "^6.0.1",
+    "ember-test-selectors": "^6.0.0",
     "ember-truth-helpers": "^4.0.3",
     "ember-uikit": "^9.1.1",
     "file-saver": "^2.0.5",
@@ -97,7 +98,6 @@
     "ember-source-channel-url": "3.0.0",
     "ember-template-lint": "5.13.0",
     "ember-template-lint-plugin-prettier": "5.0.0",
-    "ember-test-selectors": "6.0.0",
     "ember-try": "3.0.0",
     "eslint": "8.57.0",
     "eslint-config-prettier": "9.1.0",