fix(oauth): rfc8414 should judement the response_types (#485)

response_types_supported should be judement while try to do 'Authorization Code Flow'

Signed-off-by: jokemanfire <hu.dingyang@zte.com.cn>

examples/servers/src/complex_auth_streamhttp.rs

@@ -529,6 +529,7 @@ async fn oauth_authorization_server() -> impl IntoResponse {
         token_endpoint: format!("http://{}/oauth/token", BIND_ADDRESS),
         scopes_supported: Some(vec!["profile".to_string(), "email".to_string()]),
         registration_endpoint: Some(format!("http://{}/oauth/register", BIND_ADDRESS)),
+        response_types_supported: Some(vec!["code".to_string()]),
         issuer: Some(BIND_ADDRESS.to_string()),
         jwks_uri: Some(format!("http://{}/oauth/jwks", BIND_ADDRESS)),
         additional_fields,