Outdated dependencies

Actual:

```
warning microbundle > rollup-plugin-terser@7.0.2: This package has been deprecated and is no longer maintained. Please use @rollup/plugin-terser
warning microbundle > @rollup/plugin-commonjs > magic-string > sourcemap-codec@1.4.8: Please use @jridgewell/sourcemap-codec instead
warning microbundle > rollup-plugin-postcss > cssnano > cssnano-preset-default > postcss-svgo > svgo > stable@0.1.8: Modern JS already guarantees Array#sort() is a stable sort, so this library is deprecated. See the compatibility table on MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort#browser_compatibility
```

Expected:

Doesn't use deprecated and no longer maintained / outdated packages.

Would PRs be accepted that fix the reported outdated packages? I see 21 PRs in queue.

Thanks and best

Start by reproducing the reported warnings and tracing microbundle's dependency tree through rollup-plugin-terser, @rollup/plugin-commonjs, rollup-plugin-postcss, cssnano, and their transitive packages. Done means the reported deprecated or unmaintained packages are no longer present, with the relevant dependency checks passing.

Rédigé par le modèle d'indexation à partir du texte de l'issue.