Add cmake>=3.13 and mpi4py to Python Requires.

Update dependencies.

bin/dunepackaging.py

@@ -92,7 +92,7 @@ def main(argv):
     # Generate pyproject.toml
     print("Generate pyproject.toml")
     f = open("pyproject.toml", "w")
-    requires = ["setuptools", "wheel", "scikit-build", "cmake", "ninja", "requests"]
+    requires = ["setuptools", "wheel", "scikit-build", "cmake", "ninja", "requests", "portalocker", "numpy"]
     requires += data.asPythonRequirementString(data.depends + data.python_requires)
     f.write("[build-system]\n")
     f.write("requires = "+requires.__str__()+"\n")

dune.module

@@ -4,5 +4,5 @@ Author: The Dune Core developers
 Maintainer: dune-devel@lists.dune-project.org
 Description: Basis infrastructure for all Dune modules
 URL: https://gitlab.dune-project.org/core/dune-common
-Python-Requires: portalocker numpy wheel
+Python-Requires: portalocker numpy wheel mpi4py
 Whitespace-Hook: Yes