Add @types/react-router dev dependency (#105)

Co-authored-by: Enrique Moreno Cano <ecano@microsoft.com>

Author: chuwik

frontend/package.json

@@ -41,6 +41,7 @@
     "@types/qs": "^6.5.1",
     "@types/react": "^16.0.21",
     "@types/react-dom": "^16.0.2",
+    "@types/react-router": "^4.3.1",
     "@types/react-router-dom": "^4.2.0",
     "awesome-typescript-loader": "^3.3.0",
     "babel-core": "^6.26.0",