chore(deps): update devdependency knip to v6

Author: renovate[bot]

package.json

@@ -32,7 +32,7 @@
     "changelogen": "^0.6.2",
     "eslint": "^10.0.3",
     "exsolve": "^1.0.8",
-    "knip": "^5.86.0",
+    "knip": "^6.0.6",
     "nuxt": "^4.4.2",
     "pkg-pr-new": "^0.0.65",
     "semver": "^7.7.4",