suppress unused variables

src/main.cpp

@@ -34,7 +34,7 @@ int main(int argc, char* argv[]) {
 #endif // WIN32
     DebugPrintTID();
     // curl needs to be initialized to properly deallocate its resources later
-    auto ret = curl_global_init(CURL_GLOBAL_DEFAULT);
+    [[maybe_unused]] auto ret = curl_global_init(CURL_GLOBAL_DEFAULT);
     Assert(ret == CURLE_OK);
 #ifdef DEBUG
     std::thread t1(loop);