Set list-style further down the DOM

This closes https://github.com/select2/select2/issues/4225
This closes https://github.com/select2/select2/pull/4226

src/scss/theme/default/_multiple.scss

@@ -10,6 +10,10 @@
     margin: 0;
     padding: 0 5px;
     width: 100%;
+
+    li {
+      list-style: none;
+    }
   }
 
   .select2-selection__placeholder {