Bump nltk from 3.8.1 to 3.9 in the pip group

Bumps the pip group with 1 update: [nltk](https://github.com/nltk/nltk).


Updates `nltk` from 3.8.1 to 3.9
- [Changelog](https://github.com/nltk/nltk/blob/develop/ChangeLog)
- [Commits](nltk/nltk@3.8.1...3.9)

---
updated-dependencies:
- dependency-name: nltk
  dependency-type: direct:production
  dependency-group: pip
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -1,5 +1,5 @@
 diffusers==0.29.2
-nltk==3.8.1
+nltk==3.9
 PySide6==6.7.2
 requests==2.32.0
 requests_cache==1.2.1