Move to Python 3.8

Update Python base version from 3.6 to 3.8. For Zed the minimum
Python runtime versions are Python 3.8 and 3.9 [1]. As a third
Python version I also added 3.10 already.

Removed ThreadedHTTPServer and replaced it with ThreadingHTTPServer from
standard library, which is new in Python 3.7.

[1]: https://governance.openstack.org/tc/reference/runtimes/zed.html

Depends-on: https://review.opendev.org/c/openstack/octavia/+/839604

Change-Id: I4f0d640879da5afaa4694484ad4c52f25445a8ae

releasenotes/notes/move-to-python-3.8-6a29d13144e8c378.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Update Python base version from 3.6 to 3.8. As per Openstack Python
+    runtime versions policy Python 3.8 will be the the minimum Python version
+    in the Zed release cycle.

setup.cfg

@@ -7,7 +7,7 @@ author = OpenStack
 author_email = openstack-discuss@lists.openstack.org
 home_page = https://docs.openstack.org/octavia-lib/latest/
 license = Apache License, Version 2.0
-python_requires = >=3.6
+python_requires = >=3.8
 classifier =
     Development Status :: 5 - Production/Stable
     Environment :: OpenStack
@@ -18,9 +18,9 @@ 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 :: 3.10
 
 [files]
 packages =

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 2.5.0
-envlist = docs,py37,pep8
+envlist = docs,py38,pep8
 skipsdist = True
 ignore_basepython_conflict = True
 

zuul.d/projects.yaml

@@ -3,11 +3,11 @@
       - check-requirements
       - openstack-cover-jobs
       - openstack-lower-constraints-jobs
-      - openstack-python3-yoga-jobs
+      - openstack-python3-zed-jobs
       - publish-openstack-docs-pti
       - release-notes-jobs-python3
       - octavia-tox-tips
     check:
       jobs:
-        - octavia-tox-functional-py37-tips:
+        - octavia-tox-functional-py39-tips:
             voting: false