Bump nltk from 3.4 to 3.6.5 in /src/Diagnostics.AIProjects/SearchAPI

Bumps [nltk](https://github.com/nltk/nltk) from 3.4 to 3.6.5.
- [Release notes](https://github.com/nltk/nltk/releases)
- [Changelog](https://github.com/nltk/nltk/blob/develop/ChangeLog)
- [Commits](nltk/nltk@3.4...3.6.5)

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

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Author: dependabot[bot]

src/Diagnostics.AIProjects/SearchAPI/requirements.txt

@@ -1,6 +1,6 @@
 Flask==1.1.1
 flask_cors==3.0.7
-nltk==3.4
+nltk==3.6.5
 gensim==3.7.2
 requests==2.18.4
 pyjwt==1.7.1