Unsure what exactly the error message is saying or what needs to be changed. Using the command
FTL package failed error="initialize updates: failed to update metadata: update metadata: tuf: failed to decode timestamp.json: expired at 2021-06-03 14:22:39 -0700 -0700"
seems pretty straightforward and in the correct directory.
go run ./cmd/package --type=pkg --fleet-url=url --enroll-secret=secret