infra: add the missing setup-uv step

[kevinjqliu]

Rationale for this change

This is the only place where astral-sh/setup-uv step is missing in github actions.

Since uv is not setup for this github action, the Makefile script will fallback to using curl to install uv, which can cause errors in run
For example, https://github.com/kevinjqliu/iceberg-python/actions/runs/20143215308/job/57816383548?pr=30#logs

Run make install
uv not found. Installing...
curl: (22) The requested URL returned error: 504
uv venv 
make: uv: No such file or directory
make: *** [Makefile:70: setup-venv] Error 127
Error: Process completed with exit code 2.

Are these changes tested?

Are there any user-facing changes?

[geruh]

LGTM!