Temporary fix to requirements

[AndreFCruz]

Several fixes relating to required dependencies changing their behavior:

Shap

It seems shap==0.43.0 and onwards changed the name of explainer classes --- see shap/shap#3247
Pinning the shap version to prior to this change is a temporary quick fix.

Pandas

Additionally, it seems pandas==2.0 and onwards changed something about file loading that broke the notebooks. A simple fix is setting pandas to use any prior version. I fixed it to pandas>=1.3.2,<=1.5.3. I ran the AReM.ipynb notebook and it runs fine with these fixes.

Numpy

Some other quick fixes include pinning numpy to a version prior to 1.20, relating to this error:

AttributeError: module 'numpy' has no attribute 'object'.
`np.object` was a deprecated alias for the builtin `object`. To avoid this error in existing code, use `object` by itself. Doing this will not modify any behavior and is safe. 
The aliases was originally deprecated in NumPy 1.20; for more details and guidance see the original release note at:
    https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations

I didn't fix this one as it seems this older version of numpy is not compatible with arm CPUs, leading to other problems. I supposed that if you're running x86 CPUs pinning this numpy version should fix the issues.

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Closes #48 #56

Changes:

• Pinned shap version
• Pinned pandas version
• Bumped timeshap version
• Added pypi classifiers to signal that timeshap is in beta