[tune] remove tensorboardX upper bound

[matthewdeng]

Why are these changes needed?

Our python 3.11 images require protobuf>=4, which has a conflict with the existing version of tensorboardX.

This upper bound was originally added in #36643, when there was a requirement for protobuf<4.

Related issue number

Closes #42577

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    method in Tune, I've added it in doc/source/tune/api/ under the
    corresponding .rst file.
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• Testing Strategy
  • Unit tests
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  • This PR is not tested :(

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