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

Bumps [nodemailer](https://github.com/nodemailer/nodemailer) from 6.10.1 to 7.0.3.
- [Release notes](https://github.com/nodemailer/nodemailer/releases)
- [Changelog](https://github.com/nodemailer/nodemailer/blob/master/CHANGELOG.md)
- [Commits](nodemailer/nodemailer@v6.10.1...v7.0.3)

---
updated-dependencies:
- dependency-name: nodemailer
  dependency-version: 7.0.3
  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

@@ -30,7 +30,7 @@
     "fastify": "^5.3.3",
     "fastify-favicon": "^5.0.0",
     "lucia": "^3.2.2",
-    "nodemailer": "^6.9.8",
+    "nodemailer": "^7.0.3",
     "pino": "^9.7.0",
     "pino-pretty": "^13.0.0",
     "pug": "^3.0.2",