Update dependency express to v4.20.0 [SECURITY]

Author: renovate[bot]

package.json

@@ -10,7 +10,7 @@
     "heroku-postbuild": "npm run build"
   },
   "dependencies": {
-    "express": "4.16.3",
+    "express": "4.20.0",
     "vue": "2.5.17",
     "@vue/cli-service": "4.4.4" 
   },