What is the best way to rename index in liquibase?

At first, you must remove former index:

<changeSet id="20210905084713-2" author="ARMIN.NOROOZIAN">
    <dropIndex tableName="tpl_order" indexName="tracking_code_idx"/>
</changeSet>

Then create a new index:

<changeSet id="20210905084713-3" author="ARMIN.NOROOZIAN">
    <createIndex tableName="tpl_order" indexName="tpl_tracking_code_idx">
        <column name="tpl_tracking_code"/>
    </createIndex>
</changeSet>