feat: update @eslint/markdown to v6 (#606)

Author: ocavue

package.json

@@ -99,6 +99,7 @@
     "@antfu/install-pkg": "^0.4.1",
     "@clack/prompts": "^0.7.0",
     "@eslint-community/eslint-plugin-eslint-comments": "^4.4.0",
+    "@eslint/markdown": "^6.1.0",
     "@stylistic/eslint-plugin": "^2.7.2",
     "@typescript-eslint/eslint-plugin": "^8.4.0",
     "@typescript-eslint/parser": "^8.4.0",
@@ -111,7 +112,6 @@
     "eslint-plugin-import-x": "^4.2.1",
     "eslint-plugin-jsdoc": "^50.2.2",
     "eslint-plugin-jsonc": "^2.16.0",
-    "eslint-plugin-markdown": "^5.1.0",
     "eslint-plugin-n": "^17.10.2",
     "eslint-plugin-no-only-tests": "^3.3.0",
     "eslint-plugin-perfectionist": "^3.5.0",