Bump express from 4.17.1 to 4.17.3

Bumps [express](https://github.com/expressjs/express) from 4.17.1 to 4.17.3.
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/master/History.md)
- [Commits](https://github.com/expressjs/express/compare/4.17.1...4.17.3)

---
updated-dependencies:
- dependency-name: express
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -5,7 +5,7 @@
   "dependencies": {
     "@babel/runtime": "^7.4.5",
     "cors": "^2.8.5",
-    "express": "^4.17.1",
+    "express": "^4.17.3",
     "nodemon": "^1.19.1",
     "react": "^16.8.6",
     "react-dom": "^16.8.6",