fix: satosa-oidcop example conf

Author: peppelinux

example/plugins/frontends/oidcop_frontend.yaml

@@ -29,7 +29,7 @@ config:
       server_info:
         add_on:
           pkce:
-            function: idpyoidc.server.oidc.add_on.pkce.add_pkce_support
+            function: idpyoidc.server.oauth2.add_on.pkce.add_support
             kwargs:
               code_challenge_method: S256 S384 S512
               essential: false