Support @preact/signals-react 2

[luisherranz]

What

This PR adds support for @preact/signals-react v2.

Why

Because the Preact team has changed how @preact/signals-react is integrated with React and released a new major version.

How

By updating the tests, readme, peer dependencies, and useDeepSignal.

[github-actions]

Size Change: +34 B (+1%)

Total Size: 6.23 kB

Filename	Size	Change
packages/deepsignal/react/dist/deepsignal-react.js	1.07 kB	+15 B (+1%)
packages/deepsignal/react/dist/deepsignal-react.mjs	1.06 kB	+19 B (+2%)

ℹ️ View Unchanged

Filename	Size
packages/deepsignal/core/dist/deepsignal-core.js	1.01 kB
packages/deepsignal/core/dist/deepsignal-core.mjs	1 kB
packages/deepsignal/dist/deepsignal.js	1.05 kB
packages/deepsignal/dist/deepsignal.mjs	1.04 kB

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