Bump stylelint-config-standard from 20.0.0 to 21.0.0 (#85)

Bumps [stylelint-config-standard](https://github.com/stylelint/stylelint-config-standard) from 20.0.0 to 21.0.0.
- [Release notes](https://github.com/stylelint/stylelint-config-standard/releases)
- [Changelog](https://github.com/stylelint/stylelint-config-standard/blob/master/CHANGELOG.md)
- [Commits](stylelint/stylelint-config-standard@20.0.0...21.0.0)

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

package.json

@@ -28,7 +28,7 @@
   },
   "dependencies": {
     "stylelint-config-rational-order": "^0.1.2",
-    "stylelint-config-standard": "^20.0.0",
+    "stylelint-config-standard": "^21.0.0",
     "stylelint-order": "^4.1.0"
   },
   "devDependencies": {