Make Windows runner work with MPI tests

[sserita]

Describe the bug
Currently the test/test_packages/tools/test_logl.py::LogLTestCase::test_hessian_mpi and test/test_packages/extras/test_interpygate.py fail on the GitHub Windows runner with the following error:

FAILED test/test_packages/tools/test_logl.py::LogLTestCase::test_hessian_mpi - RuntimeError: cannot load MPI library
Could not find module 'C:\Users\runneradmin\AppData\Roaming\Python\DLLs' (or one of its dependencies). Try using the full path with constructor syntax.
Could not find module 'C:\Users\runneradmin\AppData\Roaming\Python\Library\bin' (or one of its dependencies). Try using the full path with constructor syntax.
Could not find module 'C:\hostedtoolcache\windows\Python\3.8.10\x64\DLLs\impi.dll' (or one of its dependencies). Try using the full path with constructor syntax.
Could not find module 'C:\hostedtoolcache\windows\Python\3.8.10\x64\DLLs\msmpi.dll' (or one of its dependencies). Try using the full path with constructor syntax.
Could not find module 'C:\hostedtoolcache\windows\Python\3.8.10\x64\Library\bin' (or one of its dependencies). Try using the full path with constructor syntax.
Could not find module 'impi.dll' (or one of its dependencies). Try using the full path with constructor syntax.
Could not find module 'msmpi.dll' (or one of its dependencies). Try using the full path with constructor syntax.

See https://github.com/sandialabs/pyGSTi/actions/runs/12794355146/job/35669306620 for an example.

We are now catching this error so that the tests pass, but we should fix this such that we run the MPI tests on Windows as well.