uv + maturin migration

[dandavison]

Migrate from poetry to uv. See temporalio/sdk-python#768

Tested via such commands as:

# with and without wheel at ../sdk-python/dist/*.whl
go run . run --lang python  --version ../sdk-python

go build -o temporal-features
./temporal-features run --version 1.9.0 --lang python continue_as_new/updates_do_not_block_continue_as_new

./temporal-features prepare --lang py --dir prepare-py --version ~/src/temporalio/sdk-python
./temporal-features run --prepared-dir prepare-py --server localhost:7233 --namespace default --lang python features/continue_as_new/updates_do_not_block_continue_as_new

./temporal-features build-image --lang python --version v1.9.0
docker run features:py-1.9.0 --lang py

[cretz]

LGTM, though leaving unapproved while the Python SDK main is not yet ready for this change

[cretz]

LGTM. Note, if anyone is running .github/workflows/python.yaml with an existing tag and version-is-repo-ref as true, this will break for them. But I am not sure anyone is.

[dandavison]

Note, if anyone is running .github/workflows/python.yaml with an existing tag and version-is-repo-ref as true, this will break for them. But I am not sure anyone is.

True. If needed we could make it work with both around https://github.com/temporalio/features/blob/uv/sdkbuild/python.go#L128-L135. E.g. inspect the pyproject.toml or try uv sync + build first and fallback to poetry install + build.