install magma for cuda 11.2 in conda (#50559)
Summary:
This PR allows us to start adding CUDA 11.2 Linux tests onto CI.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50559
Reviewed By: ejguan
Differential Revision: D26007595
Pulled By: janeyx99
fbshipit-source-id: e179dbe54e9390899d556dd201a1a179b2399d20
