feat: added alert.scss to bootstrap-custom-index.scss

Author: Hammerbak

web/profiles/custom/os2loop/themes/os2loop_theme/assets/bootstrap-custom/bootstrap-custom-index.scss

@@ -3,6 +3,7 @@
 @import "variables/variables.scss";
 @import "typography/typography.scss";
 
+@import "alert/alert.scss";
 @import "badge/badge.scss";
 @import "button-group/button-group.scss";
 @import "dropdown/dropdown.scss";