fix: upgrade express from 4.16.4 to 4.21.0

Snyk has created this PR to upgrade express from 4.16.4 to 4.21.0.

See this package in npm:
express

See this project in Snyk:
https://app.snyk.io/org/support-bot/project/817f71c9-5a85-4962-9dd5-27e48d550881?utm_source=github&utm_medium=referral&page=upgrade-pr

package.json

@@ -25,7 +25,7 @@
     "date-utils": "~1.2.21",
     "ent": "~2.2.0",
     "errorhandler": "~1.5.0",
-    "express": "~4.16.3",
+    "express": "~4.21.0",
     "grunt": "~1.0.3",
     "grunt-autoprefixer": "~3.0.4",
     "grunt-contrib-clean": "~1.1.0",