fix(ui5-li): fix styles import extension (#351)

Author: ilhan007

packages/main/src/ListItem.js

@@ -8,7 +8,7 @@ import "./CheckBox.js";
 import "./Button.js";
 
 // Styles
-import styles from "./themes/ListItem.css";
+import styles from "./themes/ListItem.css.js";
 
 /**
  * @public

packages/main/src/ListItemBase.js

@@ -4,7 +4,7 @@ import { isTabNext, isTabPrevious } from "@ui5/webcomponents-base/src/events/Pse
 import ListItemBaseTemplateContext from "./ListItemBaseTemplateContext.js";
 
 // Styles
-import styles from "./themes/ListItemBase.css";
+import styles from "./themes/ListItemBase.css.js";
 
 
 /**