Update Bindle dependency to latest stable release

[radu-matei]

ref #180, #191

Currently in Spin we are using Bindle v0.8.0.
There is a new release candidate for Bindle that would help us address #180 — however, in updating it we will encounter a few breaking changes, most notably required signing of packages when publishing, and verification when pulling (see release notes).

This issue tracks the upgrade.

[FrankYang0529]

I would like to take this issue. May you assign it to me? Thank you!

[vdice]

Spin is moving towards using OCI registries as its default form of artifact support. Full details can be seen in SIP-008: Using OCI Registries.

As we'll be devoting engineering effort to the aforementioned and due to the non-trivial impact of upgrading Bindle to the next release (which is still pending and does add breaking changes), I'd propose we close this issue -- or at least make it clear that Spin will most likely stay pinned to the 0.8.x Bindle version for the foreseeable future.