Only support openmm 7.6

[mikemhenry]

This adjusts our CI to only test 7.6 + nightly, sets the min version of openmm to 7.6 and removes and only env file.

[codecov]

Codecov Report

Merging #896 (69d94c8) into master (741dd72) will decrease coverage by 0.95%.
The diff coverage is n/a.

[mikemhenry]

@ijpulidos I got some nan's in the python 3.9 tests so I will re-run, but assuming things pass this should be good for review and merge!

[ijpulidos]

This looks good! I just think not pinning the openmm version should work better.

[ijpulidos]

I think we don't want to pin any specific openmm version. It should use the latest available and it would also not require manually changing it for future openmm releases. Isn't that the case?

[mikemhenry]

I don't think there is an issue with having to manually change as openmm releases come out since if a new version comes out that breaks things, then we would want to keep testing against the older version while we update.

[mikemhenry]

I'm open to other ideas! Also pinning the "oldest" version we support makes the logic of refining the env a bit easier in the CI, but we could probably refactor it so we don't need to do that.

[jchodera]

We should pin openmm >=7.6, not =!

[ijpulidos]

Why is it trying to test OpenMM 7.5.1 in the checks?

[mikemhenry]

Why is it trying to test OpenMM 7.5.1 in the checks?

In the settings for the repo, those checks are set to "required" so it expects them in the PR. Until we merge this one in, I didn't want to change the repo setting since that would affect other PRs.

[ijpulidos]

Minor comment, for future releases of openmm. But a non-blocker.