Revert "build(deps): bump helmet from 4.4.1 to 5.0.1"

Signed-off-by: Fredrik Adelöw <freben@gmail.com>

plugins/app-backend/package.json

@@ -39,7 +39,7 @@
     "express": "^4.17.1",
     "express-promise-router": "^4.1.0",
     "fs-extra": "9.1.0",
-    "helmet": "^5.0.1",
+    "helmet": "^4.0.0",
     "knex": "^0.95.1",
     "lodash": "^4.17.21",
     "luxon": "^2.0.2",