Add only keep latest caching option to save disk space

[panghaoyuan]

Currently computation caching is cumulative. It will affects the upload and download speed of the cache in the CI environment like gitlab and will also significantly increase the execution time of the CI.

Is it possible to add one option to only keep latest computation cache?

[anthonyshew]

A TTL should be implemented server-side in accordance with web standards. This isn't something that the turbo CLI can dictate since flags/options are mutable as a client.