Raise lower dependency constraints

[j-wags]

While we have some extensive reverse compatibility (eg our package dependencies still allow openmm 7.6), allowing such a wide range of versions is starting to choke up the mamba solver. So we should tighten pins where possible to exclude versions of deps that are eg. more than 2 years old.

[mattwthompson]

conda-forge/openff-toolkit-feedstock#125

[mattwthompson]

We decided this is mostly something that can be impacted by packaging. Updating constraints in test environments is not necessarily bad but probably doesn't change much