tests: auth_agent_nonblocking should run in nonblocking

tests/client/torture_auth.c

@@ -354,6 +354,8 @@ static void torture_auth_agent_nonblocking(void **state) {
     rc = ssh_userauth_list(session, NULL);
     assert_true(rc & SSH_AUTH_METHOD_PUBLICKEY);
 
+    ssh_set_blocking(session,0);
+
     do {
       rc = ssh_userauth_agent(session, NULL);
     } while (rc == SSH_AUTH_AGAIN);