Next 15 breaking Async Request APIs

[ChiefORZ]

Description

With the breaking change of the Next.js version 15 of the Async Request APIs we need to change the implementation of receiving the headers in Server-Side Rendering.

Currently the following error occurs, when trying to access const t = useTranslations() in an Server Component:

[ Server ]  Error: Route "/[locale]" used `headers().get('X-NEXT-INTL-LOCALE')`. `headers()` should be awaited before using its value. Learn more: https://nextjs.org/docs/messages/sync-dynamic-apis

Verifications

• I've verified that the problem I'm experiencing isn't covered in the docs.
• I've searched for similar, existing issues on GitHub and Stack Overflow.
• I've compared my app to a working example to look for differences.

Mandatory reproduction URL

https://github.com/amannn/next-intl-bug-repro-app-router

Reproduction description

git clone https://github.com/amannn/next-intl-bug-repro-app-router
cd next-intl-bug-repro-app-router
pnpm i
pnpm up next@^15
pnpm dev

Expected behaviour

Repository should be updated to support next@15

[ChiefORZ]

duplicate of #1375 (comment)

[amannn]

Please see: #1375 (comment)