MinifyJS can't be installed with mysql utf8mb4 encoding

When using utf8mb4 encoding characters can be 1,2,3 or 4 bytes long.
Mysql unique indexes only can index a maximum of 767 bytes which results in a incorrect length for unique keys:

SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes: CREATE TABLE
{minifyjs_file} (
`fid` INT unsigned NOT NULL auto_increment COMMENT 'The file id of the javascript file.', 
`uri` VARCHAR(255) NOT NULL COMMENT 'Original file uri.', 
`size` INT unsigned NOT NULL COMMENT 'Original file size.', 
`modified` INT unsigned NOT NULL COMMENT 'Original file last modified date.', 
`minified_uri` VARCHAR(255) DEFAULT '' COMMENT 'Minified file uri.', 
`minified_size` INT unsigned DEFAULT 0 COMMENT 'Minified file size.', 
`minified_modified` INT unsigned DEFAULT 0 COMMENT 'Minified file last modified date.', 
PRIMARY KEY (`fid`), 
UNIQUE KEY `uri` (`uri`)
) ENGINE = InnoDB DEFAULT CHARACTER SET utf8mb4 COMMENT 'Store a list of all javascript files and their minified…'; Array
(
)

The maximum length should be 191 when using utf8mb4 encoding.