Add py38 package metadata

Change-Id: Icbc092e85e9211c409f32767412915a3c7651dc3
diff --git a/setup.cfg b/setup.cfg
index e6277e3..ea9ab4c 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -16,6 +16,7 @@
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
+    Programming Language :: Python :: 3.8
 
 [files]
 packages =