Bump html-validate from 8.18.1 to 8.20.1 in /docs

Bumps [html-validate](https://gitlab.com/html-validate/html-validate) from 8.18.1 to 8.20.1.
- [Release notes](https://gitlab.com/html-validate/html-validate/tags)
- [Commits](https://gitlab.com/html-validate/html-validate/compare/v8.18.1...v8.20.1)

---
updated-dependencies:
- dependency-name: html-validate
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

docs/package.json

@@ -15,7 +15,7 @@
 	"devDependencies": {
 		"@biomejs/biome": "1.6.4",
 		"css-validator": "0.11.0",
-		"html-validate": "8.18.1",
+		"html-validate": "8.20.1",
 		"js-beautify": "1.14.11",
 		"raw-loader": "^4.0.2",
 		"sort-package-json": "2.10.0",