Revert "mpi4py: update to 4.0.1"
Just in case !11647 (merged) can't be merged in time for VTK 9.4.0, here's a reversion of !11589 (merged) that can be applied instead.
This reverts from mpi4py-4.0.1 back to mpi4py-3.1.4.
If merged, please re-open #19472 (closed).
Backport: release
Edited by David Gobbi