Update nltk version

[ishaaq]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...) Update dependency to conform with security advisory https://github.com/advisories/GHSA-cgvx-9447-vcch

• What is the current behavior? (You can also link to an open issue here) N/A

• What is the new behavior (if this is a feature change)? N/A

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?) N/A

• Have unit tests been run against this PR? (Has there also been any additional testing?)

• Related Python client changes (link commit/PR here) N/A

• Related documentation changes (link commit/PR here) N/A

• Other information: https://nvd.nist.gov/vuln/detail/CVE-2024-39705

• Please check if the PR fulfills these requirements

• [x] The commit message follows our guidelines
• [ ] Tests for the changes have been added (for bug fixes/features)
• [ ] Docs have been added / updated (for bug fixes / features)