fix(package): update react-focus-lock to version 2.3.1

Closes #624

Author: greenkeeper[bot]

package.json

@@ -65,7 +65,7 @@
     "react": "16.12.0",
     "react-cookie-consent": "3.0.0",
     "react-dom": "16.12.0",
-    "react-focus-lock": "2.2.1",
+    "react-focus-lock": "2.3.1",
     "react-intl": "3.10.0",
     "react-linkify": "1.0.0-alpha",
     "react-redux": "7.1.3",