Upgrade next to v14

[aspeddro]

• Fix DocSearch not scrolling to anchor element ([NEXT-658] Nextjs 13 Link not scrolling to anchor element vercel/next.js#44295)
• Remove tailwind warnings

  warn - The `@responsive` directive has been deprecated in Tailwind CSS v3.0.
  warn - Use `@layer utilities` or `@layer components` instead.
  

[vercel]

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[aspeddro]

Dependency to add support for nested declarations

 ⚠ ./node_modules/next/dist/build/webpack/loaders/css-loader/src/index.js??ruleSet[1].rules[6].one
Of[14].use[1]!./node_modules/next/dist/build/webpack/loaders/postcss-loader/src/index.js??ruleSet[
1].rules[6].oneOf[14].use[2]!./styles/_docsearch.css
Warning

(52:3) Nested CSS was detected, but CSS nesting has not been configured correctly.
Please enable a CSS nesting plugin *before* Tailwind in your configuration.
See how here: https://tailwindcss.com/docs/using-with-preprocessors#nesting

[fhammerschmidt]

Sorry, had to revert this because of #844 which is arguably a bigger bug than the scrolling bug.