arg : fix unused variable (#13142)

common/arg.cpp

@@ -673,7 +673,7 @@ static struct common_hf_file_res common_get_hf_file(const std::string &, const s
     return {};
 }
 
-std::pair<long, std::vector<char>> common_remote_get_content(const std::string & url, const common_remote_params & params) {
+std::pair<long, std::vector<char>> common_remote_get_content(const std::string &, const common_remote_params &) {
     throw std::runtime_error("error: built without CURL, cannot download model from the internet");
 }