move regx to constant

Author: MartinLenord

src/lti/LTI_Names_Roles_Provisioning_Service.php

@@ -31,7 +31,7 @@ public function get_members() {
 
             $next_page = false;
             foreach($page['headers'] as $header) {
-                if (preg_match("/^Link:.*<([^>]*)>; ?rel=\"next\"/i", $header, $matches)) {
+                if (preg_match(LTI_Service_Connector::NEXT_PAGE_REGEX, $header, $matches)) {
                     $next_page = $matches[1];
                     break;
                 }

src/lti/LTI_Service_Connector.php

@@ -4,6 +4,9 @@
 use Firebase\JWT\JWT;
 
 class LTI_Service_Connector {
+
+    const NEXT_PAGE_REGEX = "/^Link:.*<([^>]*)>; ?rel=\"next\"/i";
+
     private $registration;
     private $access_tokens = [];