feat: push docker image also to Github registry

[tobiasdiez]

Currently the docker image is only pushed to the Docker Hub repository. In certain countries dockerhub is not working very reliable, thus this PR proposes to also publish the images to the Github Packages repository.

The code is essentially taken from the cloudnative variant: https://github.com/tensorchord/cloudnative-pgvecto.rs/blob/main/.github/workflows/docker.yml

Test run currently fails already at the build step, so I don't know how to test this: https://github.com/tobiasdiez/pgvecto.rs/actions/runs/11326123877/job/31494425115

[gaocegege]

LGTM

Thanks for your contribution! 🎉 👍

cc @VoVAllen

[usamoi]

Test run currently fails already at the build step

Should be fixed now.

[tobiasdiez]

Test run currently fails already at the build step

Should be fixed now.

Thanks! I've rerun the workflow, but it's now failing because I (obviously) don't have the correct docker hub credentials: https://github.com/tobiasdiez/pgvecto.rs/actions/runs/11426048592/job/31788570283

So I have no idea how to properly test these changes. Sorry.