Add python 3.10 to setup.cfg metadata

Add python 3.10 to setup.cfg
refer to: https://governance.openstack.org/tc/reference/runtimes/2023.2.html

Change-Id: Ieffd6fa3580cfb092f8f12f0a4a932e0fbdacc67

setup.cfg

@@ -20,6 +20,7 @@ classifier =
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
+    Programming Language :: Python :: 3.10
 
 [files]
 packages =