Update pyjwt requirement from >=2.8.0 to >=2.12.1 in /backend

Updates the requirements on [pyjwt](https://github.com/jpadilla/pyjwt) to permit the latest version.
- [Release notes](https://github.com/jpadilla/pyjwt/releases)
- [Changelog](https://github.com/jpadilla/pyjwt/blob/master/CHANGELOG.rst)
- [Commits](jpadilla/pyjwt@2.8.0...2.12.1)

---
updated-dependencies:
- dependency-name: pyjwt
  dependency-version: 2.12.1
  dependency-type: direct:production
...

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Author: dependabot[bot]

backend/pyproject.toml

@@ -93,7 +93,7 @@ dependencies = [
     "tzdata>=2024.1",
     "wagtail-factories==4.2.1",
     "google-auth-oauthlib>=1.2.1",
-    "PyJWT>=2.8.0",
+    "PyJWT>=2.12.1",
     "cryptography>=43.0.0",
     "openai>=1.52.0",
     "pydantic>=2.9.2",