- Bump express from 4.16.4 to 4.20.0 in quick-start

Summary:
Bump express dependency from ^4.16.4 to ^4.20.0 in the messenger-platform-samples
quick-start sample app. This addresses the external Dependabot PR #173 on the
fbsamples/messenger-platform-samples GitHub repo.

Express 4.20.0 includes security fixes (open redirect prevention, backtracking
protection in path-to-regexp), updated default depth for URL-encoded parsing,
and removal of link renderization in redirects.

Reviewed By: shreeshyadav

Differential Revision: D99834889

fbshipit-source-id: 7ef8ec99f232bfe35757ef54cae94ef987556815

Author: Ed Papa

quick-start/package.json

@@ -9,7 +9,7 @@
   "dependencies": {
     "body-parser": "^1.20.3",
     "dotenv": "^6.2.0",
-    "express": "^4.16.4",
+    "express": "^4.20.0",
     "request": "^2.88.0"
   },
   "engines": {