Hadrien G 11340a332d [hepmc] Finish the HepMC3 spackage update (#15036) ...

* Finish the HepMC3 spackage update

- Update CMake requirement per latest master
- Account for Python variant, add python dependency if used
- Account for ROOT I/O variant, add ROOT dependency if used

* Please flake8

2020-02-18 16:04:59 -06:00

..

spack

[hepmc] Finish the HepMC3 spackage update (#15036)

2020-02-18 16:04:59 -06:00