Restrict resume file allowed mime types

gistfile1.txt

add_filter( 'submit_resume_form_fields', 'alter_allowed_mime_types' );
function alter_allowed_mime_types( $fields ) {
  if ( ! empty( $fields['resume_fields']['resume_file'] ) ) {
    $fields['resume_fields']['resume_file']['allowed_file_types'] = array(
     'doc'                          => 'application/msword',
     'docx'                         => 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
     'pdf'                          => 'application/pdf',
   );
  }
  return $fields;
}