fix(mention): use new url schema

[max-nextcloud]

📝 Summary

Fixes notifications for mentions in 28 and following.

• Resolves: Failing ci runs such as https://github.com/nextcloud/text/actions/runs/7587197071?pr=5284

🖼️ Screenshots

🏁 Checklist

• Code is properly formatted (npm run lint / npm run stylelint / composer run cs:check)
• Sign-off message is added to all commits
• Tests (unit, integration and/or end-to-end) passing and the changes are covered with tests
• Documentation is not required

[max-nextcloud]

/backport to stable28

[juliushaertl]

Thanks for looking into that Max :)

[backportbot]

The backport to stable28 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable28
git pull origin stable28

# Create the new backport branch
git checkout -b backport/5302/stable28

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 711258d7c9308b51956f1193283d9bb31d644908

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/5302/stable28

Error: Failed to push branch backport/5302/stable28: fatal: could not read Username for 'https://github.com': No such device or address

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Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[juliushaertl]

/backport to stable28