chore(deps): bump cryptography

Bumps the pip group with 1 update in the /backend directory: [cryptography](https://github.com/pyca/cryptography).


Updates `cryptography` from 46.0.5 to 46.0.6
- [Changelog](https://github.com/pyca/cryptography/blob/main/CHANGELOG.rst)
- [Commits](https://github.com/pyca/cryptography/compare/46.0.5...46.0.6)

---
updated-dependencies:
- dependency-name: cryptography
  dependency-version: 46.0.6
  dependency-type: direct:production
  dependency-group: pip
...

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

backend/requirements.txt

@@ -38,7 +38,7 @@ celery==5.6.2
 redis==7.3.0
 
 # Security & Encryption
-cryptography==46.0.5  # Updated: Fixed NULL pointer dereference (was 42.0.0)
+cryptography==46.0.6  # Updated: Fixed NULL pointer dereference (was 42.0.0)
 
 # Notifications
 apprise==1.7.1