skip test_coroutines.sh if mpi4py cannot be imported

tests/python/test_coroutines.sh.in

@@ -4,6 +4,7 @@
 # SPDX-License-Identifier: CC0-1.0
 
 @TEST_MPI_FALSE@exit 77
+@PYTHON@ -c 'import mpi4py' || exit 77
 
 PYTHONPATH="@abs_top_builddir@/python:$PYTHONPATH"
 export PYTHONPATH