FIXED revert to solid stable alpine version

.gitlab-ci.yml

 image: python:alpine
-#python:rc-alpine
-#
+#for bleeding edge (sometimes broken) use the python:rc-alpine docker image
 
 before_script:
-  # forcing pip version 19.3.1 as pip version 20.0 has https://github.com/pypa/pip/issues/7217
-  # reset to default "pip install --upgrade pip" when the issue is resolved
-  #- pip install --upgrade pip==19.3.1
-  #
   - pip install --upgrade pip
   - pip install markdown
   - pip install Pygments