chore: update dependency knip to v6 (#223)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

package.json

@@ -81,7 +81,7 @@
     "eslint-config-eslint": "^14.0.0",
     "eslint-plugin-eslint-plugin": "^7.3.2",
     "globals": "^17.0.0",
-    "knip": "^5.82.1",
+    "knip": "^6.0.0",
     "lint-staged": "^16.0.0",
     "mdast-util-from-markdown": "^2.0.2",
     "mocha": "^11.3.0",