Verify and display a nag-messsage to the log if vulnerable hash-type is used.

        :return:

def verify_hash_type(self):
        '''
        Verify and display a nag-messsage to the log if vulnerable hash-type is used.

        :return:
        '''
        if self.config['hash_type'].lower() in ['md5', 'sha1']:
            log.warning(
                'IMPORTANT: Do not use %s hashing algorithm! Please set '
                '"hash_type" to sha256 in Salt %s config!',
                self.config['hash_type'], self.__class__.__name__
            )