Our python-test-multi image installs more OS libraries, like postgresql client libraries. But there is other stuff in there as well like pymssql, odbc, etc.
I'd probably lean towards creating another mise based image with some of the libraries that will be used very often, list postgresql and the lxml libraries used by PyQuery. I'd probably leave out the stuff like pymssql and instead put the more uncommon libraries in an app-specific image built by the project. Refs #1.