Cleanup py27 support

Make a few cleanups:
- Remove python 2.7 stanza from setup.py
- Add requires on python >= 3.6 to setup.cfg so that pypi and pip
  know about the requirement
- Remove obsolete sections from setup.cfg:
  * Wheel is not needed for python 3 only repo
- Update classifiers
- Update requirements, no need for python_version anymore

Change-Id: Ic79312278978ecb5d93386fa9f4261be037611ed

doc/requirements.txt

@@ -1,6 +1,6 @@
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
-sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2;python_version>='3.4'  # BSD
+sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2  # BSD
 openstackdocstheme>=1.20.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0

setup.cfg

@@ -3,18 +3,21 @@ name = monasca-notification
 author = OpenStack
 author-email = openstack-discuss@lists.openstack.org
 summary = Reads alarms from Kafka and then notifies the customer using their configured notification method.
+python-requires = >=3.6
 classifier=
     Development Status :: 5 - Production/Stable
     License :: OSI Approved :: Apache Software License
     Topic :: System :: Monitoring
     Operating System :: POSIX :: Linux
     Programming Language :: Python
+    Programming Language :: Python :: Implementation :: CPython
+    Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
 keywords = openstack monitoring email
 description-file = README.rst
-home-page = https://github.com/openstack/monasca-notification
+home-page = https://opendev.org/openstack/monasca-notification
 license = Apache
 
 [entry_points]
@@ -35,9 +38,6 @@ autodoc_index_modules = True
 [pep8]
 max-line-length = 120
 
-[wheel]
-universal = 1
-
 [extras]
 jira_plugin =
   Jinja2>=2.10 # BSD License (3 clause)

setup.py

@@ -13,17 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# THIS FILE IS MANAGED BY THE GLOBAL REQUIREMENTS REPO - DO NOT EDIT
 import setuptools
 
-# In python < 2.7.4, a lazy loading of package `pbr` will break
-# setuptools if some other modules registered functions in `atexit`.
-# solution from: http://bugs.python.org/issue15881#msg170215
-try:
-    import multiprocessing  # noqa
-except ImportError:
-    pass
-
 setuptools.setup(
     setup_requires=['pbr>=2.0.0'],
     pbr=True)