[Feature] Tests via Github actions + README

[FlorianDeconinck]

Summary

Github actions

Restore the unit tests using Github actions. Runs serial & parallel CPU tests. GPU tests is a logged issue #7

README

Basic README describing the project and describing how to install and how to run the tests

Technical details

• Fix setup.py with bad arguments
• Align the error for non-contiguous buffer on the newer GT4Py usage of DLPack
• Deactivate the caches relocability tests when running with MPI. The test is design for a single rank and tests filepaths manipulation, and therefore doesn't required MPI.