Add python3.10 support in testing runtime

In 2023.2 cycle testing runtime, project test in py38 py39 and py10

[0] https://governance.openstack.org/tc/reference/runtimes/2023.2.html

Change-Id: Iecabd70ec401534b68ca1299feb3f1aaa631e340

Author: likui

setup.cfg

@@ -18,6 +18,7 @@ classifier =
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
+    Programming Language :: Python :: 3.10
 
 description_file =
     README.rst