Display medium size images without srcset in WordPress

functions.php

<?php
// Add support for cropping default WordPress medium images
if(!get_option("medium_crop")) {
	add_option("medium_crop", "1");
} else {
	update_option("medium_crop", "1");
}
update_option( 'medium_size_w', 200 );
update_option( 'medium_size_h', 300 );

/**
 * Disable responsive image support
 */

// Clean the up the image from wp_get_attachment_image()
add_filter( 'wp_get_attachment_image_attributes', function( $attr ) {
    if( isset( $attr['sizes'] ) ) unset( $attr['sizes'] );
    if( isset( $attr['srcset'] ) ) unset( $attr['srcset'] );
    return $attr;
}, PHP_INT_MAX );

// Override the calculated image sizes
add_filter( 'wp_calculate_image_sizes', '__return_empty_array',  PHP_INT_MAX );

// Override the calculated image sources
add_filter( 'wp_calculate_image_srcset', '__return_empty_array', PHP_INT_MAX );

// Remove the reponsive stuff from the content
remove_filter( 'the_content', 'wp_make_content_images_responsive' );
?>

index.php

<?php echo wp_get_attachment_image( $image['ID'],'medium' ); ?>