Skip tests that want to connect to the internet

--- a/test/unit_test.c
+++ b/test/unit_test.c
@@ -1680,11 +1562,9 @@ int main(void) {
   test_ws();
   test_ws_fragmentation();
   test_http_server();
-  test_http_client();
   test_http_no_content_length();
   test_http_pipeline();
   test_http_range();
-  test_mqtt();
   printf("SUCCESS. Total tests: %d\n", s_num_tests);
   return EXIT_SUCCESS;
 }

