Update nltk to the latest version

[HarshaNalluru]

Description

nltk has a newer version available. Let's bump it to keep dependencies current.

Use case

Routine dependency maintenance keeps the build healthy and up to date. This is a good first issue for a new contributor.

Proposed solution

Bump nltk to the latest release across the affected manifests and lockfiles, then open a PR. Package: https://pypi.org/project/nltk/ Contributing guide: https://github.com/usemoss/moss/blob/main/CONTRIBUTING.md

Alternatives considered

No response

[aadityakumarsah]

Attempted fix: #368

Updated nltk from 3.9.4 → 3.10.0 in all three uv.lock files. No source code changes needed — the APIs used (sent_tokenize, punkt_tab) are unchanged.
GitHub will auto-link #368 to the PR.