Upgrade pip in Python install-smoke jobs (#8247)
## Problem
The Python install-smoke matrix inherits different pip releases from its
Python 3.10, 3.11, and 3.12 container images. The Python 3.10 image can
start with pip 23.0.1, whose [PEP 658 name-normalization bug rejects
valid dependency
metadata](https://github.com/deepspeedai/DeepSpeed/actions/runs/31651849867/job/94299944361?pr=8204)
before DeepSpeed installation, while the later Python images use
unaffected pip releases.
## Approach
Upgrade pip in the shared matrix path immediately before PyTorch
installation. Keeping the upgrade common to all three Python versions
avoids image-specific pins and makes every cell select the current
compatible pip release during the run.
Signed-off-by: Masahiro Tanaka <mtanaka@anyscale.com>
