[python] Dumux is not a namespace package

python/dumux/__init__.py

@@ -9,5 +9,3 @@ DuMux is
 
 https://dumux.org/
 """
-
-__import__("pkg_resources").declare_namespace(__name__)

python/setup.py.in

-from setuptools import setup, find_namespace_packages
+from setuptools import setup
 
 setup(
     name="${ProjectName}",
@@ -6,7 +6,7 @@ setup(
     version="${ProjectVersionString}",
     author="${ProjectAuthor}",
     author_email="${ProjectMaintainerEmail}",
-    packages=find_namespace_packages(include=["dumux.*"]),
+    packages=["dumux"],
     zip_safe=0,
     package_data={"": ["*.so"]},
     install_requires="${ProjectPythonRequires}".split(" "),