Split apart python_tests.sh

[noisecapella]

We should look into running each of these steps separately in github actions so that a reformat shows up as a separate item. However I'm not sure if a failed step will block other steps from running so we should first confirm that there is a way to have steps not block other steps, which is the current behavior of python_tests.sh

https://github.com/mitodl/bootcamp-ecommerce/pull/1086/files#diff-ce149b5ed0910e5d10231e3c6144b626a115633fd40a77d6a85ec899df1e302aR18-R21