Bump tensorflow-gpu from 2.5.3 to 2.7.2 in /research/neural_clustering

Bumps [tensorflow-gpu](https://github.com/tensorflow/tensorflow) from 2.5.3 to 2.7.2.
- [Release notes](https://github.com/tensorflow/tensorflow/releases)
- [Changelog](https://github.com/tensorflow/tensorflow/blob/master/RELEASE.md)
- [Commits](tensorflow/tensorflow@v2.5.3...v2.7.2)

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

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Author: dependabot[bot]

research/neural_clustering/requirements.txt

@@ -1,3 +1,3 @@
 absl-py
 numpy
-tensorflow-gpu==2.5.3
+tensorflow-gpu==2.7.2