Add environment vars expansion and pre defined git hashes in the yaml (ploomber#120)

* Add environment vars expansion and pre defined git hashes in the yaml file

* Fix flake8 lint

* Add build time placeholder

* test fixes

* fixes

* fix

Co-authored-by: Eduardo Blancas <[email protected]>

Author: feribg

setup.cfg

@@ -1,3 +1,5 @@
 [flake8]
 # kind is a tmp directory with tutorials, we can delete it once we move their content to the docs
 exclude = build/, src/soopervisor/assets/aws-lambda/app.py, tests/assets/fast-pipeline/fast_pipeline.py, kind/
+max-line-length = 88
+extend-ignore = E203