Bump pyjwt from 2.1.0 to 2.4.0 in /containers/backend (#723)

Bumps [pyjwt](https://github.com/jpadilla/pyjwt) from 2.1.0 to 2.4.0.
- [Release notes](https://github.com/jpadilla/pyjwt/releases)
- [Changelog](https://github.com/jpadilla/pyjwt/blob/master/CHANGELOG.rst)
- [Commits](https://github.com/jpadilla/pyjwt/compare/2.1.0...2.4.0)

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

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containers/backend/requirements.txt

@@ -1,7 +1,7 @@
 Django==3.2.16
 django-cors-middleware==1.5.0
 djangorestframework==3.12.4
-PyJWT==2.1.0
+PyJWT==2.4.0
 djangorestframework-simplejwt==4.8.0
 djoser==2.1.0
 envparse==0.2.0