Woocommerce(wordpress) email type displaying ‘plain/text’ instead of ‘text/html’

The Woocommerce email settings for all the orders are showing ‘Plain text’ as Email type, it should show HTML/Multipart too, but it is restricting or overriding to Plain Text. How can we have the options of HTML/Multipart.

I have added a function below to functions.php

function wps_set_content_type(){
    return "text/html";
}
add_filter( 'wp_mail_content_type','wps_set_content_type' );

but this does not works