⬆️ Bump python in /docker

Bumps python from 3.12.0a7-slim-buster to 3.12.0b1-slim-buster.

---
updated-dependencies:
- dependency-name: python
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

docker/Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.12.0a7-slim-buster
+FROM python:3.12.0b1-slim-buster
 
 ENV LANG=C.UTF-8 \
   LC_ALL=C.UTF-8 \