Bump nodemailer from 6.9.16 to 7.0.11 in /backend

Bumps [nodemailer](https://github.com/nodemailer/nodemailer) from 6.9.16 to 7.0.11.
- [Release notes](https://github.com/nodemailer/nodemailer/releases)
- [Changelog](https://github.com/nodemailer/nodemailer/blob/master/CHANGELOG.md)
- [Commits](nodemailer/nodemailer@v6.9.16...v7.0.11)

---
updated-dependencies:
- dependency-name: nodemailer
  dependency-version: 7.0.11
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

backend/package-lock.json

@@ -37,7 +37,7 @@
     "ical-generator": "^8.0.1",
     "is-utorid": "^1.2.2",
     "node-fetch": "^2.6.12",
-    "nodemailer": "^6.9.3",
+    "nodemailer": "^7.0.11",
     "prettier": "^3.0.0",
     "winston": "^3.9.0"
   },