check curl extention

Author: ierusalim

src/ClickHouseAPI.php

@@ -42,6 +42,10 @@
  * @copyright  2017, Ierusalim
  * @license    https://opensource.org/licenses/Apache-2.0 Apache-2.0
  */
+if (!\extension_loaded("curl")) {
+    die("Error: curl php extension missing");
+}
+
 class ClickHouseAPI
 {
     /*