[http_request] Pass collect_headers by const reference instead of by value (#11494)

esphome/components/http_request/http_request_idf.cpp

@@ -55,7 +55,7 @@ esp_err_t HttpRequestIDF::http_event_handler(esp_http_client_event_t *evt) {
 std::shared_ptr<HttpContainer> HttpRequestIDF::perform(const std::string &url, const std::string &method,
                                                        const std::string &body,
                                                        const std::list<Header> &request_headers,
-                                                       std::set<std::string> collect_headers) {
+                                                       const std::set<std::string> &collect_headers) {
   if (!network::is_connected()) {
     this->status_momentary_error("failed", 1000);
     ESP_LOGE(TAG, "HTTP Request failed; Not connected to network");