Use `uv version` rather than custom sed script to update pkg version

[vdusek]

• Available from uv v0.7, see https://github.com/astral-sh/uv/releases/tag/0.7.0.
• Here: https://github.com/apify/workflows/blob/v0.29.0/.github/workflows/python_bump_and_update_changelog.yaml#L48:L54.