chore(deps-dev): Bump @vitest/coverage-istanbul from 2.1.6 to 2.1.8

Bumps [@vitest/coverage-istanbul](https://github.com/vitest-dev/vitest/tree/HEAD/packages/coverage-istanbul) from 2.1.6 to 2.1.8.
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v2.1.8/packages/coverage-istanbul)

---
updated-dependencies:
- dependency-name: "@vitest/coverage-istanbul"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -62,7 +62,7 @@
     "@nextcloud/typings": "^1.9.1",
     "@nextcloud/vite-config": "^2.2.2",
     "@types/node": "^22.10.1",
-    "@vitest/coverage-istanbul": "^2.1.6",
+    "@vitest/coverage-istanbul": "^2.1.8",
     "fast-xml-parser": "^4.5.0",
     "jsdom": "^25.0.1",
     "tslib": "^2.8.1",