Merge "Drop py36 and py37 support"

.zuul.d/xstatic-master.yaml

@@ -27,7 +27,7 @@
 
 - job:
     name: horizon-tox-py36-xstatic-master
-    parent: openstack-tox-py36
+    parent: openstack-tox-py39
     required-projects: *xstatic-projects
 
 - job:

setup.cfg

@@ -6,6 +6,7 @@ description_file =
 author = OpenStack
 author_email = openstack-discuss@lists.openstack.org
 home_page = https://docs.openstack.org/horizon/latest/
+python_requires = >=3.8
 classifier =
     Development Status :: 5 - Production/Stable
     Environment :: OpenStack
@@ -19,8 +20,6 @@ classifier =
     Programming Language :: Python
     Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.6
-    Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
     Topic :: Internet :: WWW/HTTP

setup.py

@@ -13,16 +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'],

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 3.18.0
-envlist = pep8,py36,py39,releasenotes,npm,py3-dj32
+envlist = pep8,py39,releasenotes,npm,py3-dj32
 skipsdist = True
 # Automatic envs (pyXX) will only use the python version appropriate to that
 # env and ignore basepython inherited from [testenv] if we set
@@ -13,8 +13,9 @@ usedevelop = True
 setenv =
   VIRTUAL_ENV = {envdir}
   PYTHONDONTWRITEBYTECODE = 1
+  # TODO(amotoki): There are three variants of PYTHONWARNINGS. They should be merged.
   PYTHONWARNINGS = once,ignore::PendingDeprecationWarning
-  py{3,36,37}:PYTHONWARNINGS = once,ignore::PendingDeprecationWarning,ignore::ImportWarning:backports
+  py{3,39}:PYTHONWARNINGS = once,ignore::PendingDeprecationWarning,ignore::ImportWarning:backports
   # DeprecationWarning is disabled in dj32 tox env as Django 3.2
   # deprecated Django 2.2 features. This workaround is just to reduce
   # the number of warnings due to this change.