Use python 3.11 in GAs

[eitanturok]

What does this PR do?

I set python-version to 3.11 in the pr-gpu GA and daily GA.

What issue(s) does this change relate to?

The pr-gpu GA and daily GA both used an image with python 3.11 mosaicml/pytorch:2.2.1_cu121-python3.11-ubuntu20.04 but had python-version: 3.9. This PR makes the image and python-version consistent by setting the python-version to 3.11.

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