deps(backend): bump litellm to 1.101.0 - #831

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/add-to-project@v1.0.2, actions/checkout@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/