Support push and load being set together

[PeterJCLaw]

Description

Currently if the action is passed both load: true and push: true then it emits an error:

ERROR: push and load may not be set together at the moment

It would be great if these options were supported at the same time.

Alternatively, it would be great if there was some more explanation as to why this isn't supported (it doesn't feel like it'd be hard to support?) and suggestions for what to do instead.

[crazy-max]

ERROR: push and load may not be set together at the moment

Yes multiple exporters are currently not supported but will be in near future, see moby/buildkit#4134

[PeterJCLaw]

Aha, thanks :)

[tonynajjar]

Can we keep this Issue open to track when this feature is available with build-push-action. I'm assuming some changes are needed in this repo as well

[crazy-max]

Can we keep this Issue open to track when this feature is available with build-push-action. I'm assuming some changes are needed in this repo as well

No changes needed, will be available as soon as GitHub Runners update to future buildx version

[tonynajjar]

Great, then you might want to update #727 as well