fix: upgrade helmet from 3.21.3 to 3.23.3

Snyk has created this PR to upgrade helmet from 3.21.3 to 3.23.3.

See this package in npm:
https://www.npmjs.com/package/helmet

See this project in Snyk:
https://app.snyk.io/org/pedro.borracha/project/f8e01535-b97e-48ae-938a-041d30bf170c?utm_source=github&utm_medium=upgrade-pr

Author: snyk-bot

package-lock.json

@@ -38,7 +38,7 @@
     "country-code-lookup": "0.0.17",
     "emoji-flags": "^1.2.0",
     "express": "^4.17.1",
-    "helmet": "^3.21.3",
+    "helmet": "^3.23.3",
     "humanize-number": "0.0.2",
     "lodash": "^4.17.15",
     "moment": "^2.24.0",