build(deps): bump @testing-library/react in /frontend (#31)

Bumps [@testing-library/react](https://github.com/testing-library/react-testing-library) from 14.1.2 to 15.0.7.
- [Release notes](https://github.com/testing-library/react-testing-library/releases)
- [Changelog](https://github.com/testing-library/react-testing-library/blob/main/CHANGELOG.md)
- [Commits](https://github.com/testing-library/react-testing-library/compare/v14.1.2...v15.0.7)

---
updated-dependencies:
- dependency-name: "@testing-library/react"
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

frontend/package.json

@@ -7,7 +7,7 @@
     "@pdf-lib/fontkit": "^1.1.1",
     "@reduxjs/toolkit": "^2.2.2",
     "@testing-library/jest-dom": "^6.4.2",
-    "@testing-library/react": "^14.0.0",
+    "@testing-library/react": "^15.0.7",
     "@testing-library/user-event": "^14.5.1",
     "@types/jest": "^29.5.6",
     "@types/node": "^20.8.9",