Add defer tag to OM plugin embed scripts

om-defer-embed-scripts.php

<?php 
add_filter( 'optin_monster_api_final_output', function( $campaigns ) {
	if ( ! empty( $campaigns ) ) {
		foreach ( $campaigns as $slug => $embed ) {
			$campaigns[ $slug ] = str_replace( 's.async=true;', 's.async=true;s.defer=true;', $embed );
		}
	}

	return $campaigns;
} );