Bump python from 3.12.2-alpine to 3.12.3-alpine in /assets

Bumps python from 3.12.2-alpine to 3.12.3-alpine.

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

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

assets/Dockerfile

@@ -1,7 +1,7 @@
 # Copyright (c) 2018 Anton Semjonov
 # Licensed under the MIT License
 
-FROM python:3.12.2-alpine
+FROM python:3.12.3-alpine
 
 # default cron schedule
 ENV SCHEDULE="*/15 * * * *"