Docker rate limit errors when using `fly deploy`

This incident is now resolved, Depot builders should be working correctly now.

We're still rolling out configurations to mitigate this issue. Note that this issue only affects users with builders in some US regions. In the meanwhile, trying the recommended workarounds, or relocating your builder (Settings -> App builders) to either Dallas, Chicago or Toronto should allow your builds to complete successfully.

We've identified the root cause for this issue and are implementing mitigations.

We are investigating sporadic build failures mentioning Docker rate limits on "unauthenticated pulls" and error 429.

In the meantime, workarounds to try in order are:
1. Use `fly deploy --depot=false`
2. Use `fly deploy --buildkit`
3. Install Docker locally and use `--local-only` with Fly deploy