fix(deps): bump nuxt from 2.15.0 to 2.15.4

Bumps [nuxt](https://github.com/nuxt/nuxt.js) from 2.15.0 to 2.15.4.
- [Release notes](https://github.com/nuxt/nuxt.js/releases)
- [Changelog](https://github.com/nuxt/nuxt.js/blob/dev/RELEASE_PLAN.md)
- [Commits](nuxt/nuxt@v2.15.0...v2.15.4)

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

Author: dependabot[bot]