Removed unused dependency

Author: pascalgagneur

package-lock.json

@@ -74,7 +74,6 @@
     "jsdom": "^9.12.0",
     "mocha": "^5.2.0",
     "nyc": "^11.0.2",
-    "react-addons-test-utils": "^15.6.2",
     "react-test-renderer": "^16.0.0",
     "sinon": "^7.1.0",
     "styled-components": "^4.1.3",