Bump @wordpress/stylelint-config from 21.4.0 to 21.7.0 (#118)

Bumps [@wordpress/stylelint-config](https://github.com/WordPress/gutenberg/tree/HEAD/packages/stylelint-config) from 21.4.0 to 21.7.0.
- [Release notes](https://github.com/WordPress/gutenberg/releases)
- [Changelog](https://github.com/WordPress/gutenberg/blob/trunk/packages/stylelint-config/CHANGELOG.md)
- [Commits](https://github.com/WordPress/gutenberg/commits/@wordpress/stylelint-config@21.7.0/packages/stylelint-config)

---
updated-dependencies:
- dependency-name: "@wordpress/stylelint-config"
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -44,7 +44,7 @@
     "@wordpress/dependency-extraction-webpack-plugin": "^4.7.0",
     "@wordpress/env": "^5.9.0",
     "@wordpress/eslint-plugin": "^13.8.0",
-    "@wordpress/stylelint-config": "^21.4.0",
+    "@wordpress/stylelint-config": "^21.7.0",
     "archiver": "^5.3.1",
     "babel": "^6.23.0",
     "babel-loader": "^9.1.0",