CI/CD pipeline to build on main commit and publish to PyPI on release 4

.gitlab-ci.yml

@@ -5,7 +5,9 @@ default:
       - .pip-cache/
   before_script:
     - python3 --version
-    - python3 -m ensurepip --upgrade
+    - curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
+    - python3 get-pip.py
+    - pip install --upgrade pip
     - pip install build twine
 
 stages: