normalise project name (adher to PEP 625)

[boegel]

Got a notification after v0.5.0 was published:

In the future, PyPI will require all newly uploaded source distribution filenames to comply with PEP 625. Any source distributions already uploaded will remain in place as-is and do not need to be updated.

Specifically, your recent upload of 'eessi-testsuite-0.5.0.tar.gz' is incompatible with PEP 625 because it does not contain the normalized project name 'eessi_testsuite'.

In most cases, this can be resolved by upgrading the version of your build tooling to a later version that supports PEP 625 and produces compliant filenames.