Revise tests around scikit-hep-testdata v0.4.3+

[matthewfeickert]

trafficstars

Following up on discussion in Issue #76, the files added in https://github.com/scikit-hep/scikit-hep-testdata/pull/56 are in scikit-hep-testdata v0.4.3+. The test should be restructured around this.

[eduardo-rodrigues]

Should we close this at this point? We had several updates related to tests, with some using new files in scikit-hep-testdata. I would say we're now using what we have available, and it is more a matter of getting newer files. No point in having issue open with no concrete plan behind them.