Update python image version and reduce size for gallery docker image (#4686)

* Update python image version and reduce size

Update python image to 3.13
Reduce size by adding `--no-install-recommands` and removing `/var/lib/apt/lists/*`

* Use python base image without minor version

Use python:3-slim instead of python:3.13-slim as base image for the gallery Dockerfile

* Update CHANGES.md

---------

Co-authored-by: Cooper Lees <me@cooperlees.com>