Release 0.3.0

[lucab]

Relevant changes:

• dkregistry: remove tokio-core, use tokio instead
• client: add an ensure_v2 helper
• blobs: switch from hyper to reqwest
• lib/get_credentials: include unfound index in error message
• manifest/v2s1: add get_labels() method, test and example
• dkregistry: format with 1.31.0 toolchain
• cargo/maintainers: add Stefan Junker

[lucab]

/cc @steveej

[steveej]

Any chance you verified the validity of #56?

[steveej]

We should get #82 into this release.

[lucab]

Rebased to include #82. The first commit in the series is equivalent to #56. We should have done that when we actually did the API break, I can split it out of this release PR if you prefer for clarity.

[steveej]

The first commit in the series is equivalent to #56.

That PR adds a new environment variable and doesn't do a version bump. Where's the equivalence? 🔍

[lucab]

I'm closing this for now as we are piling up a few more bits. I'll trigger another release attempt once PR queue is drained again.