Remove dependency on six
@ralbertazzi 
This issue is closed when the [PR](https://github.com/tensorflow/tensorflow/pull/59617) is merged.

Thank you ! I think we have some clean up to do before getting rid of six; let me get back to you on this. Hi, thanks for bringing this to our attention! Yeah, we should definitely get rid of six, but we have some lingering places in the codebase where it's still in use, which is my blocker for approving the merge. Feel free to add that to this PR, or we also can get rid of the usages, although no promises on the timeline for that, unfortunately.
<details><summary>Click to expand!</summary> 
 
 ### Issue Type

Build/Install

### Have you reproduced the bug with TF nightly?

Yes

### Source

source

### Tensorflow Version

2.13.0

### Custom Code

Yes

### OS Platform and Distribution

_No response_

### Mobile device

_No response_

### Python version

_No response_

### Bazel version

_No response_

### GCC/Compiler version

_No response_

### CUDA/cuDNN version

_No response_

### GPU model and memory

_No response_

### Current Behaviour?

Tensorflow [relies on six](https://github.com/tensorflow/tensorflow/blob/c746206c1a377fe8f5571511a778993701d10ecc/tensorflow/tools/pip_package/setup.py#L109) as direct dependency. Since Tensorflow [requires Python >= 3.8](https://github.com/tensorflow/tensorflow/blob/c746206c1a377fe8f5571511a778993701d10ecc/tensorflow/tools/pip_package/setup.py#L357) and `six` is a Python 2 and 3 compatibility library, I'm sure it should be possible to remove this unneeded dependency and rely on Python 3 stdlib


### Standalone code to reproduce the issue

Irrelevant


### Relevant log output

_No response_</details>