Add macOS uv instructions to installations.md

[sangbida]

Changelog-None

Important

25.09 FREEZE July 28TH: Non-bugfix PRs not ready by this date will wait for 25.12.

RC1 is scheduled on August 11th

The final release is scheduled for September 1st.

Checklist

Before submitting the PR, ensure the following tasks are completed. If an item is not applicable to your PR, please mark it as checked:

• The changelog has been updated in the relevant commit(s) according to the guidelines.
• Tests have been added or modified to reflect the changes.
• Documentation has been reviewed and updated as needed.
• Related issues have been listed and linked, including any that this PR closes.