Bump tensorflow from 2.8.0 to 2.8.1 in /cvat/requirements (#4)

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 2.8.0 to 2.8.1.
- [Release notes](https://github.com/tensorflow/tensorflow/releases)
- [Changelog](https://github.com/tensorflow/tensorflow/blob/master/RELEASE.md)
- [Commits](tensorflow/tensorflow@v2.8.0...v2.8.1)

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

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cvat/requirements/base.txt

@@ -37,7 +37,7 @@ h5py==3.6.0
 django-cors-headers==3.5.0
 furl==2.1.0
 av==8.0.2 --no-binary=av
-tensorflow==2.8.0 # Optional requirement of Datumaro. Use tensorflow-macos==2.8.0 for Mac M1
+tensorflow==2.8.1 # Optional requirement of Datumaro. Use tensorflow-macos==2.8.0 for Mac M1
 # The package is used by pyunpack as a command line tool to support multiple
 # archives. Don't use as a python module because it has GPL license.
 patool==1.12