Update donatj/mddoc requirement from ^0.8.0 to ^0.8.0 || ^0.9.0

Updates the requirements on [donatj/mddoc](https://github.com/donatj/mddoc) to permit the latest version.
- [Release notes](https://github.com/donatj/mddoc/releases)
- [Commits](donatj/mddoc@v0.8.0...v0.9.0)

---
updated-dependencies:
- dependency-name: donatj/mddoc
  dependency-type: direct:development
...

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

composer.json

@@ -15,7 +15,7 @@
 	"require-dev": {
 		"corpus/coding-standard": "~0.8.0",
 		"donatj/drop": "^1.1",
-		"donatj/mddoc": "^0.8.0",
+		"donatj/mddoc": "^0.8.0 || ^0.9.0",
 		"friendsofphp/php-cs-fixer": "^3.16",
 		"phpstan/phpstan": "^1.10",
 		"phpunit/phpunit": "^10",