[Scitech] Gromacs bump

[Christoph Junghans]

Hi,

I was holding back on packaging gromacs 2020 as it missed some essential
features, e.g. tabulated interactions, but now as gromacs 2021 is out and
the features are still missing, I am wondering if it is still reasonable to
hold back. The features are promised from gromacs 2022.

As many users still need the legacy features, I was thinking to fork
gromacs-2019 into a separate package, called "gromacs2019" or something,
and bump the normal gromacs package to v2021. Or do you guys have a better
idea?

Cheers,

Christoph