Bump tensorflow from 2.5.0 to 2.5.1 in /tests/tf-vision/model-server

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 2.5.0 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@v2.5.0...v2.5.1)

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

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

tests/tf-vision/model-server/requirements.txt

@@ -1,3 +1,3 @@
 tensorflow_hub==0.6.0
-tensorflow==2.5.0
+tensorflow==2.5.1
 Pillow==8.3.2