[alternativeLinks] Alternative links is not added to the header

[dimylkas]

Description

Alternative links is not added to the header

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://next-intl-example-app-router.vercel.app/en

Reproduction description

Steps to reproduce:
Build site
Open - and check the links

`import { defineRouting } from "next-intl/routing";

const locales = ["en", "de", "fr", "pt", "es", "ru", "it", "pl", "nl", "ro", "ua", "sr", "hr"] as const;

export const defaultLocale = "en";

export const routing = defineRouting({
locales,
defaultLocale,
localePrefix: {
mode: "as-needed",
},
});
`

Expected behaviour

Alternative links are added to the header as described here https://next-intl-docs.vercel.app/docs/routing#alternate-links