Add more python templates
This MR adds more python templates for the following actions
| Job | Action |
|---|---|
.python:base |
python job, with pip caching and default image, no script
|
.python:dist |
python setup.py sdist bdist_wheel |
.python:pytest |
python -m pytest |
.python:mkdocs |
mkdocs build |
.python:sphinx |
sphinx-build |
/cc @leo-singer