build(deps-dev): bump @pinia/testing from 0.1.5 to 0.1.6 in /frontend

Bumps [@pinia/testing](https://github.com/vuejs/pinia) from 0.1.5 to 0.1.6.
- [Release notes](https://github.com/vuejs/pinia/releases)
- [Commits](https://github.com/vuejs/pinia/compare/@pinia/testing@0.1.5...@pinia/testing@0.1.6)

---
updated-dependencies:
- dependency-name: "@pinia/testing"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

frontend/package.json

@@ -84,7 +84,7 @@
   "devDependencies": {
     "@eslint-community/eslint-plugin-eslint-comments": "^4.3.0",
     "@intlify/eslint-plugin-vue-i18n": "^3.0.0",
-    "@pinia/testing": "^0.1.5",
+    "@pinia/testing": "^0.1.6",
     "@storybook/addon-essentials": "^8.3.4",
     "@storybook/addon-interactions": "^8.3.4",
     "@storybook/addon-links": "^8.3.4",