Allow .ts files to be found in DEFAULT_FILTER option

Hello ! I'm making a discord bot using discord.js-commando and i migrate my bot to a typescript project

I figure out an issue with require-all@3.0.0 that is used by discord.js-commando@latest doesn't allow .ts files to be found by default

Maybe you should change the DEFAULT_FILTER regex from `/^([^\.].*)\.js(on)?$/` to `/^([^\.].*)\.(?:j|t)s(on)?$/`