Bump ubuntu in /docker/production/django

Bumps ubuntu from jammy-20230816 to jammy-20230916.

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

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

Author: dependabot[bot]

docker/production/django/Dockerfile

@@ -1,5 +1,5 @@
 # because ubuntu-jammy uses python3 for latest python3.10 and pip3
-FROM ubuntu:jammy-20230816
+FROM ubuntu:jammy-20230916
 
 # Create it as a "system" user without a home directory (-r)
 # Do not force a specific numeric uid