chore(deps): update dependency nuxt to v2.15.6

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
nuxt	2.15.5 -> 2.15.6

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Release Notes

nuxt/nuxt.js

### [`v2.15.6`](https://togithub.com/nuxt/nuxt.js/releases/v2.15.6) [Compare Source](https://togithub.com/nuxt/nuxt.js/compare/v2.15.5...v2.15.6) ##### 🐛 Bug Fixes - `types` - [#​9270](https://togithub.com/nuxt/nuxt.js/issues/9270) Pin to `@types/webpack-dev-middleware@4.1.2` (resolves [#​9268](https://togithub.com/nuxt/nuxt.js/issues/9268))

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Configuration

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[codecov[bot]]

Codecov Report

Merging #197 (3921911) into master (5602f34) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #197   +/-   ##
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  Coverage   96.07%   96.07%           
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  Files           2        2           
  Lines          51       51           
  Branches       13       13           
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  Hits           49       49           
  Misses          2        2