Enhance workflow

[crazy-max]

@psampaz First of all thank you for this great project! Really useful!

As a modest gift, here is a PR that offers some enhancements for the current workflow:

• Use buildx bake and goreleaser
• Create artifacts with artifact (current platform) or artifact-all target for cross-compilation:
  • darwin/amd64
  • darwin/arm64
  • linux/amd64
  • linux/arm/v6
  • linux/arm/v7
  • linux/arm64
  • windows/amd64
• Sandboxed vendor and lint validation with bake targets
• Fix go.sum
• Mutualize tests and handle them through bake and GitHub Actions with coverage
• Update codecov/codecov-action to v2
• Support Docker multi-platform image
• GitHub Actions
  • On git push tag event semver like v0.9.0:
    • Artifacts will be available in the pipeline through actions/upload-artifact
    • Will create the GitHub Release and push artifacts
    • Will create and push Docker tags psampaz/go-mod-outdated:0.9.0 / psampaz/go-mod-outdated:latest
  • On git push (master branch)
    • Artifacts will be available in the pipeline through actions/upload-artifact
    • Will push Docker tag psampaz/go-mod-outdated:edge
  • On git pull_request event
    • Artifacts will be available in the pipeline through actions/upload-artifact

Everything is already in place and tested on https://github.com/crazy-max/go-mod-outdated as well as the GitHub Actions pipeline if you want to take a look.

https://github.com/crazy-max/go-mod-outdated/releases/tag/v0.9.0

https://hub.docker.com/r/crazymax/go-mod-outdated/tags?page=1&ordering=last_updated