Update .gitlab-ci.yml

.gitlab-ci.yml

@@ -2,7 +2,9 @@ image: python:rc-alpine
 #python:alpine
 
 before_script:
-  - pip install --upgrade pip
+  # forcing version 20.0.1 as 20.0.2 has https://github.com/pypa/pip/issues/7217
+  # reset to default "pip install --upgrade pip" when the issue is resolved
+  - pip install --upgrade pip==20.0.1
   - pip install markdown
   - pip install Pygments
   - pip install mkdocs