Fix package json

Author: aurimasc

TestProjects/com.unity.mobile-notifications-sample/Packages/manifest.json

@@ -3,7 +3,6 @@
     "com.unity.ide.rider": "1.2.1",
     "com.unity.ide.visualstudio": "2.0.9",
     "com.unity.ide.vscode": "1.2.3",
-    "com.unity.mobile-notifications-sample": "file:../../com.unity.mobile-notifications-sample",
     "com.unity.mobile.notifications": "file:../../../com.unity.mobile.notifications",
     "com.unity.ugui": "1.0.0",
     "com.unity.modules.androidjni": "1.0.0",