CI refactor, publish image to GHCR

[bjw-s]

This PR makes it so that the resulting Docker image is pushed to GitHub Container registry

This PR also aims to improve the CI by

• use docker buildx to perform the multiarch build
• moving some things to the Dockerfile build
• use available GitHub actions to reduce the amount of scripting in the pipeline
• use native GitHub concurrency to make sure only a single docker build runs at a given time

Because the resulting manifest is now a true multi-arch manifest, the tagging scheme has been changed. This could be considered a "breaking" change in SemVer terms.

Fixes #324

Working example (I have only commented out the actual image pushing and logging in to Docker Hub): https://github.com/bjw-s/dsmr-reader-docker/actions/runs/4438109116

[xirixiz]

Love it @bjw-s ! really appreciate this improvement! Sometimes it's "just" working and improvements will then only happen when there is some spare time left. This removes a lot of unnecessary build code as well.

I`ll validate it and merge it Tonight.

[bjw-s]

Love it @onedr0p! I really appreciate this improvement! Sometimes it's "just" working and improvements will then only happen when there is some spare time left. This removes a lot of unnecessary build code as well.

I`ll validate it and merge it Tonight.

@onedr0p is not stealing my thunder again 😝 (he'll understand the joke there) But I am glad that you like the changes. I'm doing some final tests (hence the force pushes) but those will be done in a little bit are done now

[xirixiz]

Everything is working like a charm @bjw-s. Many thanks again for this great contribution. In the next release I`ll manage your name in the README ✌️

[bjw-s]

Sweet! Glad it's working as designed :) Thanks for merging!