Include Preact signal

Hey there,

thank you for providing `htm` and thus a simple build tools free solution to use Preact!

Recently a new extension to Preact has been published, namely [@preact/signals](https://github.com/preactjs/signals). As this is an amazing improvement to the way to use Preact I am wondering if there are any plans to include it into the whole `htm` standalone package?

This would be amazing.

Thanks you very much!

Sincerely,
Happy Striker