This switches to `async-tar` to point to our fork, which has a fix for a
bug that is causing the Cursor ACP agent fail to download in Zed, due to
Pax attributes.

We will switch back as soon as
https://github.com/dignifiedquire/async-tar/pull/73 is merged.

Closes #62655

Release Notes:

- Fixed an issue where the Cursor ACP agent would fail to start