Bump tensorflow from 2.4.0 to 2.5.1

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 2.4.0 to 2.5.1.
- [Release notes](https://github.com/tensorflow/tensorflow/releases)
- [Changelog](https://github.com/tensorflow/tensorflow/blob/master/RELEASE.md)
- [Commits](tensorflow/tensorflow@v2.4.0...v2.5.1)

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

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

Author: dependabot[bot]

requirements.txt

@@ -7,4 +7,4 @@ sklearn
 tqdm==4.28.1
 matplotlib==2.2.3
 pyaudio==0.2.11
-tensorflow==2.4.0
+tensorflow==2.5.1