Do not create a universal wheel for the release.

The package is Python 3 only.
And zest.releaser.create-wheel is not needed, since we already have a bdist_wheel section.

setup.cfg

@@ -7,10 +7,9 @@ ignore =
 
 [zest.releaser]
 python-file-with-version = src/icalendar/__init__.py
-create-wheel = yes
 
 [bdist_wheel]
-universal = 1
+universal = 0
 
 [metadata]
 license_files = LICENSE.rst