Bump tensorflow from 1.15.4 to 2.9.3

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 1.15.4 to 2.9.3.
- [Release notes](https://github.com/tensorflow/tensorflow/releases)
- [Changelog](https://github.com/tensorflow/tensorflow/blob/master/RELEASE.md)
- [Commits](tensorflow/tensorflow@v1.15.4...v2.9.3)

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

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

Author: dependabot[bot]

requirements.txt

@@ -1,4 +1,4 @@
-tensorflow==1.15.4
+tensorflow==2.9.3
 tensorflowjs==1.7.4
 numpy==1.21.0
 matplotlib==3.2.1