Bump stylelint from 7.13.0 to 9.9.0

Bumps [stylelint](https://github.com/stylelint/stylelint) from 7.13.0 to 9.9.0.
- [Release notes](https://github.com/stylelint/stylelint/releases)
- [Changelog](https://github.com/stylelint/stylelint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/stylelint/stylelint/compare/7.13.0...9.9.0

)

Signed-off-by: dependabot[bot] <support@dependabot.com>

package.json

@@ -6,7 +6,7 @@
   "license": "MIT",
   "bugs": "https://github.com/pmarsceill/just-the-docs/issues",
   "devDependencies": {
-    "stylelint": "^7.13.0",
+    "stylelint": "^9.9.0",
     "stylelint-config-primer": "^2.2.11"
   },
   "dependencies": {},