Make a 0.13.0 that doesn't have GAFF support (#329)
a. Point users towards 0.12.0 which still does, with limitations (Python 3.10, AmberTools 22, x86 architecture only)
a. These limitations don't apply to the SMIRNOFF template generator
When AmberTools 24 is packaged, test this package alongside it
b. Currently expect it to work (no new GAFF version) but hard to predict prior to testing
AmberTools23 includes a new GAFF version (2.2.20, March 2021). From the header:
We should add this GAFF version and update other force fields we are able to.