Build and push multi-arch docker images

[Schmitze333]

Automate the build and provisioning of docker images to the jacobbednarz/go-csp-collector docker hub repo.

As discussed in #90, a new multi-arch image is now built when a new release is done (or a git tag is pushed manually).

For this to work two conditions have to be fulfilled:

1. As already mentioned in the issue, the two repository secrets DOCKERHUB_USERNAME and DOCKERHUB_TOKEN have to be present for the action.
2. A release Github release has to be based on a tag (or a corresponding tag has to be pushed manually).

Open for any suggestions/improvements.

[jacobbednarz]

nice work here @Schmitze333 👏 i'm seeing both latest and 0.0.14 updated with both architectures in docker hub.