Drop the zope.app.testing extra.

It dropped its special ``zope.testbrowser`` support and we do not need it for
our tests or code any more.

CHANGES.txt

@@ -2,9 +2,15 @@
 CHANGES
 =======
 
-2.1 (unreleased)
+3.0 (unreleased)
 ================
 
+Backwards incompatible changes
+------------------------------
+
+- Drop the ``zope.app.testing`` extra introduced in version 2.0.0 as
+  it dropped its special ``zope.testbrowser`` support.
+
 - Adapt the code to newer ``lxml`` versions which no longer raise an exception
   if the string to be parsed by ``lxml.etree`` is empty. We now raise a
   ``ValueError`` in this case.

setup.py

@@ -24,15 +24,14 @@ def read(*rnames):
 
 test_requires = [
     'zope.testrunner',
-    'zope.app.testing < 4',
     'zope.app.wsgi[testlayer] >= 4.0dev',
     'zope.app.zcmlfiles',
     'zope.app.server',
     'zope.testbrowser[test]',
 ]
 
 setup(name='z3c.etestbrowser',
-      version='2.1.dev0',
+      version='3.0.dev0',
       author='Christian Theune',
       author_email='mail@gocept.com',
       description='Extensions for zope.testbrowser',
@@ -65,7 +64,6 @@ def read(*rnames):
       tests_require=test_requires,
       extras_require={
           "test": test_requires,
-          "zope.app.testing": ["zope.app.testing < 4.0"],
       },
       install_requires=[
           'setuptools',