Bump django from 3.2.19 to 3.2.20 in /docs

Bumps [django](https://github.com/django/django) from 3.2.19 to 3.2.20.
- [Commits](django/django@3.2.19...3.2.20)

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

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

docs/requirements.txt

@@ -1,3 +1,3 @@
 # For autodoc to work.
-django==3.2.19
+django==3.2.20
 pytest==7.2.2