Update celery requirement from ==5.3.* to ==5.4.* in /server (#75)

Updates the requirements on [celery](https://github.com/celery/celery) to permit the latest version.
- [Release notes](https://github.com/celery/celery/releases)
- [Changelog](https://github.com/celery/celery/blob/main/Changelog.rst)
- [Commits](celery/celery@v5.3.0a1...v5.4.0)

---
updated-dependencies:
- dependency-name: celery
  dependency-type: direct:production
...

Author: dependabot[bot]

server/requirements.txt

@@ -2,7 +2,7 @@
 aiofile==3.8.*
 aiohttp==3.10.10
 beautifulsoup4==4.12.*
-celery==5.3.*
+celery==5.4.*
 channels==4.1.*
 channels_redis==4.2.*
 Django==4.2.*