Drop support for py36

Change-Id: I3d7162f63791362b45a3d65502c9d488615af485

.zuul.yaml

@@ -40,7 +40,6 @@
       # on-demand pipeline used to test older (but still supported) versions of python,
       # as well as intermediate releases that the openstack-python3-jobs might skip
       jobs:
-        - openstack-tox-py36
         - openstack-tox-py37
         - openstack-tox-py38
         - openstack-tox-py310

setup.cfg

@@ -13,7 +13,7 @@ project_urls =
     Documentation = https://docs.openstack.org/python-swiftclient/latest/
     Release Notes = https://opendev.org/openstack/python-swiftclient/src/branch/master/ChangeLog
     Source Code = https://opendev.org/openstack/python-swiftclient
-python_requires = >=3.6
+python_requires = >=3.7
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -23,7 +23,6 @@ classifier =
     Operating System :: Microsoft :: Windows
     Programming Language :: Python
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9