Bump eslint-plugin-jsx-a11y from 6.8.0 to 6.9.0 in /frontend

Bumps [eslint-plugin-jsx-a11y](https://github.com/jsx-eslint/eslint-plugin-jsx-a11y) from 6.8.0 to 6.9.0.
- [Release notes](https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/releases)
- [Changelog](https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/main/CHANGELOG.md)
- [Commits](jsx-eslint/eslint-plugin-jsx-a11y@v6.8.0...v6.9.0)

---
updated-dependencies:
- dependency-name: eslint-plugin-jsx-a11y
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

frontend/package.json

@@ -70,7 +70,7 @@
     "eslint-config-mantine": "^3.2.0",
     "eslint-plugin-import": "^2.29.0",
     "eslint-plugin-jest": "^28.6.0",
-    "eslint-plugin-jsx-a11y": "^6.8.0",
+    "eslint-plugin-jsx-a11y": "^6.9.0",
     "eslint-plugin-react": "^7.34.0",
     "eslint-plugin-react-hooks": "^4.6.0",
     "eslint-plugin-testing-library": "^6.2.0",