Build(deps): bump nltk from 3.8 to 3.8.1

Bumps [nltk](https://github.com/nltk/nltk) from 3.8 to 3.8.1.
- [Changelog](https://github.com/nltk/nltk/blob/develop/ChangeLog)
- [Commits](nltk/nltk@3.8...3.8.1)

---
updated-dependencies:
- dependency-name: nltk
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>