fix: upgrade helmet from 6.1.2 to 6.1.5 (#190)

Snyk has created this PR to upgrade helmet from 6.1.2 to 6.1.5.

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

See this project in Snyk:
https://app.snyk.io/org/nc-minh/project/2be35f06-8317-474e-b72a-1e47f55c131f?utm_source=github&utm_medium=referral&page=upgrade-pr

Co-authored-by: snyk-bot <snyk-bot@snyk.io>

package.json

@@ -49,7 +49,7 @@
     "express": "^4.18.2",
     "google-auth-library": "^8.7.0",
     "googleapis": "^111.0.0",
-    "helmet": "^6.1.2",
+    "helmet": "^6.1.5",
     "jsonwebtoken": "^8.5.1",
     "mongoose": "^6.10.5",
     "multer": "^1.4.5-lts.1",