Update react-router requirement from ~4.1.0 to ~4.3.1

Updates the requirements on [react-router](https://github.com/ReactTraining/react-router) to permit the latest version.
- [Release notes](https://github.com/ReactTraining/react-router/releases)
- [Changelog](https://github.com/ReactTraining/react-router/blob/master/CHANGES.md)
- [Commits](https://github.com/ReactTraining/react-router/commits/v4.3.1)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot-support

package.json

@@ -73,7 +73,7 @@
     "rc-tools": "8.x",
     "react": "^16.0.0",
     "react-dom": "^16.0.0",
-    "react-router": "~4.1.0",
+    "react-router": "~4.3.1",
     "react-router-dom": "^4.1.0",
     "react-test-renderer": "^16.0.0",
     "tslint-config-prettier": "^1.17.0",