ci: use python ubuntu image

Author: maciejmajek

.github/workflows/mkdocs-build.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on:
       - self-hosted
     container:
-      image: ubuntu:24.04
+      image: ubuntu/python:3.12-24.04_stable
 
     steps:
       - uses: actions/checkout@v4