chore(deps): bump transformers to 5.13.1 across uv lockfiles (#370)

## Summary

Bumps the `transformers` package to the latest release, **5.13.1**, in
every project that locks it.

`transformers` is not a direct dependency anywhere in the repo — it is
pulled in transitively (e.g. via `livekit-plugins-turn-detector`), so no
manifest (`pyproject.toml`) changes were needed. Each affected project
was updated with:

```
uv lock --upgrade-package transformers
```

## Affected lockfiles

| Project | Before | After |
|---|---|---|
| examples/voice-agents/insurance-adjuster | 5.12.1 | 5.13.1 |
| examples/voice-agents/candidate-screening | 5.8.0 | 5.13.1 |
| examples/voice-agents/mortgage-lending | 5.8.0 | 5.13.1 |
| examples/voice-agents/airline-pnr | 5.8.0 | 5.13.1 |
| apps/livekit-moss-vercel/.../livekit-moss-agent | 5.0.0rc3 | 5.13.1 |
| apps/pipecat-moss/ollama-local | 5.3.0 | 5.13.1 |
| apps/pipecat-moss/hume-ollama-local | 5.4.0 | 5.13.1 |
| moss-live-labs/examples/voice-agent | 5.5.4 | 5.13.1 |
| moss-live-labs/examples/advanced-voice-agent | 5.7.0 | 5.13.1 |

The resolver also bumped `safetensors` to 0.8.0 where the new
transformers version requires it, and removed a no-longer-needed
`typer-slim` entry in one lock.

Note: `transformers` matches in `pnpm-lock.yaml` files refer to
`@shikijs/transformers` (an unrelated JS package) and were intentionally
left untouched.

Closes #365

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: 3 people