NPM(deps): Bump @wordpress/compose from 6.20.0 to 6.21.0

Bumps [@wordpress/compose](https://github.com/WordPress/gutenberg/tree/HEAD/packages/compose) from 6.20.0 to 6.21.0.
- [Release notes](https://github.com/WordPress/gutenberg/releases)
- [Changelog](https://github.com/WordPress/gutenberg/blob/trunk/packages/compose/CHANGELOG.md)
- [Commits](https://github.com/WordPress/gutenberg/commits/@wordpress/[email protected]/packages/compose)

---
updated-dependencies:
- dependency-name: "@wordpress/compose"
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>