Dropping support for python < 3.8

All supported branches support python 3.8 as min
python version, updating the stackviz python
support accordingly.

Change-Id: I70661e3cd6e62a5e8948dcf55f904f7a53912e1a

.zuul.yaml

@@ -35,9 +35,6 @@
     check:
       jobs:
       - openstack-tox-pep8
-      - openstack-tox-py35
-      - openstack-tox-py36
-      - openstack-tox-py37
       - openstack-tox-py38
       - openstack-tox-py39
       - openstack-tox-py310
@@ -58,9 +55,6 @@
     gate:
       jobs:
       - openstack-tox-pep8
-      - openstack-tox-py35
-      - openstack-tox-py36
-      - openstack-tox-py37
       - openstack-tox-py38
       - openstack-tox-py39
       - openstack-tox-py310

setup.cfg

@@ -6,7 +6,7 @@ description_file =
 author = OpenStack
 author_email = openstack-discuss@lists.openstack.org
 home_page = https://docs.openstack.org/stackviz/latest/
-python_requires = >=3.5
+python_requires = >=3.8
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -17,11 +17,10 @@ classifier =
     Programming Language :: Python :: Implementation :: CPython
     Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.5
-    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
+    Programming Language :: Python :: 3.11
 
 [files]
 packages =