Bump tensorflow in /tensorflow/lite/micro/examples/magic_wand/train

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 2.0.0-beta1 to 2.5.3.
- [Release notes](https://github.com/tensorflow/tensorflow/releases)
- [Changelog](https://github.com/tensorflow/tensorflow/blob/master/RELEASE.md)
- [Commits](tensorflow/tensorflow@v2.0.0-beta1...v2.5.3)

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

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

Author: dependabot[bot]

tensorflow/lite/micro/examples/magic_wand/train/requirements.txt

@@ -1,2 +1,2 @@
 numpy==1.16.2
-tensorflow==2.4.0
+tensorflow==2.5.3