Fix deprecation in CI Sync TRL skills

[albertvillanova]

Fix deprecation in CI Sync TRL skills.

Currently, a warning is emitted by GH Action "Sync TRL skill with huggingface/skills", step "Create GitHub App token" using "actions/create-github-app-token" GH Action: https://github.com/huggingface/trl/actions/runs/28205349188/job/83554678491

Create GitHub App token
Input 'app-id' has been deprecated with message: Use 'client-id' instead.

This PR updates the input parameter for the actions/create-github-app-token action, replacing deprecated app-id with client-id in the .github/workflows/sync-huggingface-skills.yml file.

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Note

Low Risk
One-line CI workflow input rename with the same secret value; no application or security logic changes.

Overview
Updates the Sync TRL skill with huggingface/skills workflow so the actions/create-github-app-token step uses client-id instead of the deprecated app-id input.

The secret name (APP_ID_HUB_SKILLS_REPO) is unchanged; only the action input key matches the current API and removes the CI warning.

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[bot-ci-comment]

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