Update vitest to v4

Author: renovate[bot]

package.json

@@ -69,7 +69,7 @@
     "@eslint/js": "9.38.0",
     "@stylistic/eslint-plugin": "5.5.0",
     "@types/node": "22.18.13",
-    "@vitest/coverage-v8": "3.2.4",
+    "@vitest/coverage-v8": "4.1.8",
     "@vitest/eslint-plugin": "1.4.0",
     "benchmark": "2.1.4",
     "eslint": "9.38.0",