bootc expects `org.opencontainers.image.version` to be set as a label, not an annotation

Hello,

I stumbled across a minor issue with the way bootc looks for an image's version (when using `bootc status`).
It expects the version to be set as a label either with the key `org.opencontainers.image.version` or with the key `version` (see [this function](https://github.com/bootc-dev/bootc/blob/b1fe5d697855189f64ba87cff5cfb058f91792f6/crates/ostree-ext/src/container/mod.rs#L605)).

However, the OpenContainers image specification only defines `org.opencontainers.image.version` as a key inside annotations (see [here](https://specs.opencontainers.org/image-spec/annotations/#pre-defined-annotation-keys)).

To match the OpenContainers spec, would it be possible to change `version_for_config` to look for `org.opencontainers.image.version` in the annotations, then look for `version` in the labels, or would this be considered too much of a breaking change?

Best regards,
François