CI/CD pipeline to build on main commit and publish to PyPI on release 7

.gitlab-ci.yml

@@ -5,6 +5,8 @@ default:
       - .pip-cache/
   before_script:
     - python3 --version
+    - apt update
+    - apt install -y python3-pip
     - pip3 install --upgrade pip
     - pip3 install build twine