Change password link is not replaced correctly in language string newloginnotificationbodyfull in case, when forgottenpasswordurl is set in site.

Proposed fix for this:

diff --git a/lib/classes/task/send_login_notifications.php b/lib/classes/task/send_login_notifications.php
index e32cf28d06a..d6c2c765a49 100644
--- a/lib/classes/task/send_login_notifications.php
+++ b/lib/classes/task/send_login_notifications.php
@@ -61,7 +61,11 @@ class send_login_notifications extends adhoc_task {
         $userauth = get_auth_plugin($USER->auth);
         if ($userauth->can_change_password()) {
             if ($changepwurl = $userauth->change_password_url()) {
-                $changepasswordlink = $changepwurl;
+                if ($changepwurl instanceof \moodle_url) {
+                    $changepasswordlink = $changepwurl->out(false);
+                } else {
+                    $changepasswordlink = (string)$changepwurl;
+                }
             } else {
                 $changepasswordlink = (new \moodle_url('/login/change_password.php'))->out(false);
             }