Resolve security issue CVE-2021-23369

[elghailani]

This PR resolve the newly published critical security issue CVE-2021-23369 : Remote code execution in handlebars when compiling templates

[Kocal]

And resync the yarn.lock for applying your last changes on the package.json! :)

[weaverryan]

Hi!

Just a clarification for anyone else: this is a require-dev dependency - there is no security issue with Encore. If you are using handlebars in your app, then you have it installed directly and need to manage its version independent of Encore :).

But I will merge this (when it's ready - the lock file needs to be updated and recommitted) - it will help recommend to people that their version is lower than what we support.

[elghailani]

Thanks @Kocal & @weaverryan for the feedbacks.
The lock file is synched.

[weaverryan]

Thanks for putting this together @elghailani!