v0.0.2b4

Pre-release. Supersedes 0.0.2b3.

Fixes 0.0.2b3

0.0.2b3 was tagged on main, which does not carry the upgrade-exec CLI command that the
v1 to v2 upgrade flow invokes in the pod. Every upgraded run installing that version failed
with:

Usage: pyflyte-migrate [OPTIONS] ...
Try 'pyflyte-migrate --help' for help
Error

This release is cut from upgrade-exec (the same branch 0.0.2b2 came from), so
pyflyte-migrate upgrade-exec is present again, with the annotation fix cherry-picked on top.

Included

• Keep _task annotations lazy so the shim imports on older flytekit (#61).
  flytekit.Cache is only referenced in annotations; evaluating them eagerly broke
  import flyte_migrate on v1 images built against older flytekit with
  AttributeError: module 'flytekit' has no attribute 'Cache'.