Bump tensorflow from 2.4.0 to 2.11.1

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 2.4.0 to 2.11.1.
- [Release notes](https://github.com/tensorflow/tensorflow/releases)
- [Changelog](https://github.com/tensorflow/tensorflow/blob/master/RELEASE.md)
- [Commits](tensorflow/tensorflow@v2.4.0...v2.11.1)

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

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Author: dependabot[bot]

requirements.txt

@@ -2,7 +2,7 @@ numpy==1.17.3
 Keras==2.3.1
 matplotlib==3.1.1
 pandas==0.25.2
-tensorflow==2.4.0
+tensorflow==2.11.1
 nltk==3.4.5
 jupyter_core==4.6.1
 jupyter==1.0.0