Modify setup.py to avoid crash due to version 4.0.0 of mpi4py during installation (#181)

* Require mpi4py < 4

---------

Co-authored-by: Benjamin Rodenberg <benjamin.rodenberg@cit.tum.de>

Author: NiklasVin

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * Use `copy(deepcopy=True)` when checkpointing to make checkpointing more user-friendly and secure. IMPORTANT: might increase runtime, please open an issue if you face serious problems. [#172](https://github.com/precice/fenics-adapter/pull/172)
 * Add unit tests for checkpointing. [#173](https://github.com/precice/fenics-adapter/pull/173)
+* Add required version of `mpi4py` to `<4` to avoid crash during installation. [#181](https://github.com/precice/fenics-adapter/pull/181)
 * Remove checks for FEniCS installation and python3 from `setup.py` since the approach is deprecated. [#182](https://github.com/precice/fenics-adapter/pull/182)
 
 ## 2.1.0

setup.py

@@ -16,6 +16,6 @@
       author_email='info@precice.org',
       license='LGPL-3.0',
       packages=['fenicsprecice'],
-      install_requires=['pyprecice>=3.0.0.0', 'scipy', 'numpy>=1.13.3, <2', 'mpi4py'],
+      install_requires=['pyprecice>=3.0.0.0', 'scipy', 'numpy>=1.13.3, <2', 'mpi4py<4'],
       test_suite='tests',
       zip_safe=False)