message: fix: z-index for ng-outer-menu
  Changed the z-index of ng-outer-menu to 3, so that it remains always visible when opened on top of a .input-group.form-control element.  .input-group .form-control has a z-index of 2 and thus was visible on top of the dropdown
diff: @@ -222,7 +222,7 @@ ng-select {
  position: absolute;
  top: 100%;
  width: 100%;
  - z-index: 1;
  + z-index: 3;
  -webkit-overflow-scrolling: touch;
  }
  .ng-menu {
  