Fix PostCommit Python Dependency and PreCommit Python ML tests

[akashorabek]

Fixes: #31285, #30799
Successful PostCommit Python Dependency example: https://github.com/akashorabek/beam/actions/runs/14305849321
Successful PreCommit Python ML tests with ML deps installed example: https://github.com/akashorabek/beam/actions/runs/14305842322

Explicitly installed latest accelerate for tests that require the latest version of transformers (4.51.0), since otherwise it throws the error: "NameError: name 'init_empty_weights' is not defined". The solution is described here. Also switched from encode to tokenize in langchain_test.py.

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[akashorabek]

Apparently, this is a known issue where the encode function adds 2 extra tokens. Replaced it with tokenize since it solved the problem here.

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[Amar3tto]

Run Prism_Python PreCommit 3.12

[damccorm]

Thanks!