chore(deps): update vitest monorepo to v4

Author: renovate[bot]

package.json

@@ -69,8 +69,8 @@
     "@typescript-eslint/rule-tester": "^7.18.0",
     "@u3u/eslint-config": "^2.15.2",
     "@u3u/prettier-config": "^5.2.0",
-    "@vitest/coverage-v8": "^2.1.9",
-    "@vitest/ui": "^2.1.9",
+    "@vitest/coverage-v8": "^4.0.8",
+    "@vitest/ui": "^4.0.8",
     "dedent": "^1.7.0",
     "eslint": "^8.57.1",
     "eslint-doc-generator": "^1.7.1",
@@ -81,7 +81,7 @@
     "simple-git-hooks": "^2.13.1",
     "tsup": "^8.5.0",
     "typescript": "^5.9.3",
-    "vitest": "^2.1.9"
+    "vitest": "^4.0.8"
   },
   "peerDependencies": {
     "eslint": ">=8.0.0"