mfem variant hypre is now rolled into variant mpi - so update spec accordingly
mfem@4.0.1-xsdk+superlu-dist is broken and unsupported - so disable it
with the addition of py-petsc4py@3.13.0 - conretizer gets confused and is not picking py-petsc4py@3.12.0 as a compatible dependency with petsc@3.12. So manually specify it.
Also depends_on('py-libensemble@0.5.2+petsc4py ^py-petsc4py@3.12.0' causes concretizer to hang forever
3a3f871718