Default to GD

Found the solution myself here:

https://github.com/getsource/default-to-gd/blob/master/default-to-gd.php

function ms_image_editor_default_to_gd( $editors ) {
	$gd_editor = 'WP_Image_Editor_GD';

	$editors = array_diff( $editors, array( $gd_editor ) );
	array_unshift( $editors, $gd_editor );

	return $editors;
}
add_filter( 'wp_image_editors', 'ms_image_editor_default_to_gd' );