Bump nltk from 3.6.5 to 3.6.6 (#51)

Bumps [nltk](https://github.com/nltk/nltk) from 3.6.5 to 3.6.6.
- [Release notes](https://github.com/nltk/nltk/releases)
- [Changelog](https://github.com/nltk/nltk/blob/develop/ChangeLog)
- [Commits](nltk/nltk@3.6.5...3.6.6)

---
updated-dependencies:
- dependency-name: nltk
  dependency-type: indirect
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]