Bump stylelint-config-standard from 20.0.0 to 21.0.0 (#461)

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

@@ -51,7 +51,7 @@
     "lint-staged": "^10.5.4",
     "prettier": "^2.2.1",
     "stylelint": "^13.12.0",
-    "stylelint-config-standard": "^20.0.0",
+    "stylelint-config-standard": "^21.0.0",
     "stylelint-scss": "^3.19.0"
   },
   "husky": {