build(deps): bump nltk from 3.4.5 to 3.5

Bumps [nltk](https://github.com/nltk/nltk) from 3.4.5 to 3.5.
- [Release notes](https://github.com/nltk/nltk/releases)
- [Changelog](https://github.com/nltk/nltk/blob/develop/ChangeLog)
- [Commits](nltk/nltk@3.4.5...3.5)

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

Author: dependabot-preview[bot]

requirements.txt

@@ -9,7 +9,7 @@ imgurpython==1.1.7
 isodate==0.6.0
 lxml==4.5.0
 multidict==4.7.5
-nltk==3.4.5
+nltk==3.5
 psutil==5.7.0
 py-irclib==0.2.1
 requests==2.23.0