Fix Metadata Handling and Manifest Creation for Multi-Architecture Docker Builds

[Bcoderx6]

This PR resolves issues related to metadata handling, manifest creation, and multi-architecture Docker image builds in the CI/CD pipeline. The following key improvements have been made:

• Improved Metadata Logging: Added a step to log the metadata JSON output to ensure that tags and other relevant fields are properly captured and debugged.
• Fixed Tag Extraction: Updated the use of jq to correctly extract and format tags from the metadata JSON, ensuring that tags are properly applied during manifest creation.
• Enhanced Manifest Creation: Implemented a loop to iterate over each platform digest, creating and pushing the manifest for all specified platforms. This ensures that all architecture digests are processed correctly.
• Debug Steps Added: Additional logging and debug steps to trace issues with platforms, digests, and metadata.
• Platform Support: Support for amd64 and 386 platforms is maintained, and other platforms such as arm/v7, arm64, and ppc64le are prepared for future inclusion once issues are resolved.

This PR aims to fix build and push issues, particularly when creating multi-architecture manifests for the Docker registry.

@viferga

[viferga]

You truly caught the issue with your commit related to architectures, it was here:
https://github.com/metacall/guix/pull/7/files#diff-5c3fa597431eda03ac3339ae6bf7f05e1a50d6fc7333679ec38e21b337cb6721R74

As there was many other changers that were irrelevant, I have ended up making the changes directly into master, here are the commits:

• The first one solves the architecture thing you pointed out in your PR: 51aea85
• The second one solves the tagging issue, changing master into latest and implementing for the first time versioning: 5d82fcf

You can check out here that it worked:
https://hub.docker.com/repository/docker/metacall/guix/tags

I am going to close the PR as it is working on master. Thanks for your catch mate.