chore(backend): bump nodemailer in /services/backend

Bumps [nodemailer](https://github.com/nodemailer/nodemailer) from 8.0.11 to 9.0.0.
- [Release notes](https://github.com/nodemailer/nodemailer/releases)
- [Changelog](https://github.com/nodemailer/nodemailer/blob/master/CHANGELOG.md)
- [Commits](nodemailer/nodemailer@v8.0.11...v9.0.0)

---
updated-dependencies:
- dependency-name: nodemailer
  dependency-version: 9.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

services/backend/package.json

@@ -42,7 +42,7 @@
     "lucia": "^3.2.2",
     "nanoid": "^5.1.6",
     "node-cron": "^4.2.1",
-    "nodemailer": "^8.0.2",
+    "nodemailer": "^9.0.0",
     "pg": "^8.18.0",
     "pino": "^10.3.1",
     "pino-pretty": "^13.1.3",