Changes message to warning on room reservation form validation.

polaris.module

@@ -226,7 +226,7 @@ function polaris_room_reservation_form_validate(&$form, FormStateInterface $form
         $profile->save();
 
         // Alert staff that the account has been created for them.
-        \Drupal::service('messenger')->addMessage(new TranslatableMarkup('This Polaris user (' . $patron->barcode . ') has never logged in before, so we\'ve added their account to the website just now. Please try submitting your reservation again.'));
+        \Drupal::service('messenger')->addWarning(new TranslatableMarkup('This Polaris user (' . $patron->barcode . ') has never logged in before, so we\'ve added their account to the website just now. Please try submitting your reservation again.'));
       }
     }
   }