Fix unformattable cURL error code

src/solar-logger/main.cpp

@@ -81,7 +81,10 @@ std::optional<std::string> FetchDataFromURL(const std::string & url, const unsig
     const auto result = curl_easy_perform(curl);
     if(result)
     {
-        spdlog::error("Failed to fetch data from URL {} with cURL error code {}", url.c_str(), result);
+        spdlog::error(
+            "Failed to fetch data from URL {} with cURL error code {}",
+            url.c_str(),
+            static_cast<int>(result));
         curl_easy_cleanup(curl);
         return {};
     }