text: Title: [INFRA] Test import as part of ci
  Body: **Is your feature request related to a problem? Please describe.**
  
  Every month or two we get a failed release b/c unit tests pass, but something wrong with the exports means post-install import actually fails. E.g., https://github.com/graphistry/pygraphistry/pull/550 .
  
  **Describe the solution you'd like**
  
  As part of `ci` + `publish`, we should test a flow of `pip install ...` => `import graphistry; print(graphistry.__version__)`
  
  * ci: we can likely do a `pip install -i  http://...` using the git checkout hash => github url
  * publish: after the `test.pypi.org` publish, we can do a `pip install -i http://test.pypi.org/...` of the specific version
  
  