r-matrix ABI incompatibility

[mfansler]

The r-matrix package had ABI changes introduced in 1.6_2 (see conda-forge/r-matrix-feedstock#42). To prevent end-users from encountering runtime errors, metadata should be updated on all r-lme4 builds that linked to pre-1.6_2 versions of r-matrix. That would impact builds prior to 1.1_35.1 build 1 (the first to introduce a r-matrix >=1.6_2 constraint. It is unclear how far back this would need to go.