Remove support for Python 3.6 and 3.7

Maintaining support for older not supported in Zed Python versions
would take too much effort with a lot of libraries dropping
compatibility with 3.6 and 3.7

Change-Id: I58a810d8cf4247153623c247de71f774928653aa

releasenotes/notes/py36-37-bye-bye-f3268421bf6c5bb4.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Virtualbmc does not support Python 3.6 and 3.7 anymore, please use
+    version 3.8 or higher.
+

setup.cfg

@@ -6,7 +6,7 @@ description_file =
 author = OpenStack
 author_email = openstack-discuss@lists.openstack.org
 home_page = https://docs.openstack.org/virtualbmc/latest/
-python_requires = >=3.6
+python_requires = >=3.8
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -17,8 +17,6 @@ classifier =
     Programming Language :: Python :: Implementation :: CPython
     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
 

zuul.d/project.yaml

@@ -7,9 +7,7 @@
       - release-notes-jobs-python3
     check:
       jobs:
-        - openstack-tox-py36
         - virtualbmc-tempest-ironic
     gate:
       jobs:
-        - openstack-tox-py36
         - virtualbmc-tempest-ironic