Bump nuxt from 2.14.12 to 2.15.3 in /frontend

Bumps [nuxt](https://github.com/nuxt/nuxt.js) from 2.14.12 to 2.15.3.
- [Release notes](https://github.com/nuxt/nuxt.js/releases)
- [Changelog](https://github.com/nuxt/nuxt.js/blob/dev/RELEASE_PLAN.md)
- [Commits](nuxt/nuxt@v2.14.12...v2.15.3)

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