Drop py3.6 and py3.7 from Tempest

In zed cycle, OpenStack projects and oslo lib
has dropped the py3.6 and py3.7 support

- https://governance.openstack.org/tc/reference/runtimes/zed.html

With oslo not supporting the py3.6 and py3.7, Tempest master is
failing and cannot be run on py3.6|7 env.

- https://bugs.launchpad.net/tempest/+bug/1975036

We discussed about how to solve it in ML[1] and QA meeting[2] and
decided to drop it from Tempest too. Stable branches testing from
stable/victoria to stable/yoga (currently supported branch by Tempest
master) can be tested on py3.8 or if cloud run those releases on py3.6
then Tempest can be run in virtual env with py38.

Closes-Bug: #1975036

[1] http://lists.openstack.org/pipermail/openstack-discuss/2022-May/028622.html
[2] https://meetings.opendev.org/irclogs/%23openstack-qa/%23openstack-qa.2022-05-24.log.html#t2022-05-24T15:31:51

Change-Id: Ie844887a798a006794729e733748ceaa5e06d2db

releasenotes/notes/drop-py-3-6-and-3-7-a34f2294f5341539.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Python 3.6 and 3.7 support has been dropped. Last release of Tempest
+    to support python 3.6 and 3.7 is Temepst 30.0.0. The minimum version
+    of Python now supported by Tempest is Python 3.8.

setup.cfg

@@ -6,7 +6,7 @@ description_file =
 author = OpenStack
 author_email = openstack-discuss@lists.openstack.org
 home_page = https://docs.openstack.org/tempest/latest/
-python_requires = >=3.6
+python_requires = >=3.8
 classifier =
     Intended Audience :: Information Technology
     Intended Audience :: System Administrators
@@ -15,8 +15,6 @@ classifier =
     Operating System :: POSIX :: Linux
     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
     Programming Language :: Python :: 3 :: Only

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = pep8,py36,py39,bashate,pip-check-reqs
+envlist = pep8,py39,bashate,pip-check-reqs
 minversion = 3.18.0
 skipsdist = True
 ignore_basepython_conflict = True

zuul.d/project.yaml

@@ -8,9 +8,6 @@
     check:
       jobs:
         - openstack-tox-pep8
-        # TODO(gmann): run these jobs once bug#1975036 is resolved
-        #- openstack-tox-py36
-        #- openstack-tox-py37
         - openstack-tox-py38
         - openstack-tox-py39
         - tempest-full-parallel:
@@ -132,9 +129,6 @@
     gate:
       jobs:
         - openstack-tox-pep8
-        # TODO(gmann): run these jobs once bug#1975036 is resolved
-        # - openstack-tox-py36
-        # - openstack-tox-py37
         - openstack-tox-py38
         - openstack-tox-py39
         - tempest-slow-py3: