JInstaller: :Install: Error SQL Specified key was too long; max key length is 767 bytes

Extension Install: SQL error processing query: DB function failed with error number 1071 
Specified key was too long; max key length is 767 bytes
SQL =

CREATE TABLE IF NOT EXISTS  `#__answers_attachments` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `item_id` int(10) unsigned DEFAULT NULL,
  `item_type` int(10) unsigned NOT NULL,
  `filename` varchar(255) NOT NULL DEFAULT '',
  `downloads` int(10) unsigned NOT NULL DEFAULT '0',
  `created_by` int(10) unsigned NOT NULL DEFAULT '0',
  `hash` varchar(32) DEFAULT NULL,
  `filesize` int(11) unsigned NOT NULL DEFAULT '0',
  `folder` varchar(255) NOT NULL DEFAULT 'media/communityanswers/attachments',
  `filetype` varchar(20) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_unique_answer_filename` (`item_id`,`item_type`,`filename`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 DEFAULT COLLATE=utf8mb4_unicode_ci;

Package Install: There was an error installing an extension: com_communityanswers.zip