Bump gutenberg from 608b890 to 6fbc6c7

Bumps [gutenberg](https://github.com/WordPress/gutenberg) from `608b890` to `6fbc6c7`.
- [Release notes](https://github.com/WordPress/gutenberg/releases)
- [Commits](WordPress/gutenberg@608b890...6fbc6c7)

---
updated-dependencies:
- dependency-name: gutenberg
  dependency-type: direct:production
...

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