Enh support tf216 keras3

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Overview

Closes #3645

Description of the changes proposed in this pull request:

• updated tests to work with keras3 + tensorflow 2.16

Checklist

• All pre-commit checks pass.
• Unit tests added (if fixing a bug or adding a new feature)

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@connortann : I remember we had this error before while package installation:

 ERROR: THESE PACKAGES DO NOT MATCH THE HASHES FROM THE REQUIREMENTS FILE. If you have updated the package versions, please update the hashes. Otherwise, examine the package contents carefully; someone may have tampered with them.
    unknown package:
        Expected sha256 d7599b65c7af7abbc978dbf345712c60fd596aa5670496561cc10e8a71cebfb2
             Got        1f3afff1ebaea3408018256dccf958cd167e3815cfab29253155063ee7ac51c5

What was the solution? Removing the current caches?

On a side note: do we have more than 10GB cache size: https://github.com/shap/shap/actions/caches (see Approaching total cache storage limit (14.48 GB of 10 GB Used))?

[connortann]

As I recall, that issue was just a transient network issue. Re-running the CI job seemed to fix the issue and the downloaded packages matched the expected hashes.

Regarding cache size, yes I think we might approach or occasionally exceed that limit. I remember doing a fair bit of trial-and-error trying to determine which packages could be cached by pip on CI, without exceeding the total limit. My notes from that experimentation are here:

dsgibbons#42 (comment)

As per that thread, we decided to cache only a couple of packages, aiming to keep each cache under 2GB total so that the total 10GB cache. This was then implemented here:

dsgibbons#84

[connortann]

This looks great! Over to you to merge when ready.

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@connortann Thanks for the review. Will merge on green.