packaging: fix indentation of trove classifier for audience

Author: dhellmann

setup.cfg

@@ -14,7 +14,7 @@ classifier =
     Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
     Programming Language :: Python :: 3.11
-Intended Audience :: Developers
+    Intended Audience :: Developers
     Environment :: Console
 keywords =
     virtualenv