Update jinja2 requirement from >=3.1.3 to >=3.1.6 in /backend

Updates the requirements on [jinja2](https://github.com/pallets/jinja) to permit the latest version.
- [Release notes](https://github.com/pallets/jinja/releases)
- [Changelog](https://github.com/pallets/jinja/blob/main/CHANGES.rst)
- [Commits](pallets/jinja@3.1.3...3.1.6)

---
updated-dependencies:
- dependency-name: jinja2
  dependency-version: 3.1.6
  dependency-type: direct:production
...

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

Author: dependabot[bot]

backend/pyproject.toml

@@ -86,7 +86,7 @@ dependencies = [
     "wagtail-localize==1.13",
     "celery==5.5.3",
     "wagtail-headless-preview==0.8.0",
-    "Jinja2>=3.1.3",
+    "Jinja2>=3.1.6",
     "icalendar>=5.0.11",
     "pyclamd>=0.4.0",
     "magika==0.6.2",