CI/CD pipeline to build on main commit and publish to PyPI on release 6

.gitlab-ci.yml

 default:
-  image: python:3.11
+  image: python:3.11-bookworm
   cache:
     paths:
       - .pip-cache/
   before_script:
     - python3 --version
-    - python3 -m pip install --upgrade pip
-    - python3 -m pip install build twine
+    - pip3 install --upgrade pip
+    - pip3 install build twine
 
 stages:
   - build