Use native namespace packages for zest.releaser.

This is instead of deprecated pkg_resources based ones.

Note that this can be a problem in case `zest.releaser` is installed in combination with other packages in the `zest` namespace.
But there are only a few such Plone related packages, so they won't usually be installed in the same virtual environment.
And otherwise I can make new releases of those packages.
Now seems a good time to do this.

CHANGES.rst

@@ -4,6 +4,8 @@ Changelog for zest.releaser
 9.0.0 (unreleased)
 ------------------
 
+- Use native namespace packages for ``zest.releaser``, instead of deprecated ``pkg_resources`` based ones.
+
 - Changed build system to pypa/build instead of explicitly using
   setuptools.
 

setup.py

@@ -1,10 +1,8 @@
-from setuptools import find_packages
 from setuptools import setup
 
 
 setup(
-    packages=find_packages(),
-    namespace_packages=["zest"],
+    packages=["zest.releaser"],
     include_package_data=True,
     zip_safe=False,
 )

tox.ini

@@ -8,4 +8,4 @@ deps =
     zest.releaser[test]
     zest.releaser[recommended]
 commands =
-    zope-testrunner --test-path=. --tests-pattern=^tests$ {posargs:-v -c}
+    zope-testrunner --test-path={toxinidir} -s zest.releaser --tests-pattern=^tests$ {posargs:-v -c}