Use tokio_tar instead of async_tar (#1170)
## Summary
`tokio_tar` is a fork of `async_tar` that uses Tokio instead of
`async-std`. Using it removes a significant dependency from our tree.
(There is an open PR
(https://github.com/dignifiedquire/async-tar/pull/41) in `async-tar` to
add Tokio support, but it's over a year old.)
See:
https://github.com/astral-sh/puffin/pull/1157#discussion_r1469190249.
