chore: Add multi-arch docker image

[jb-abbadie]

Description

Add multi-arch docker image to goreleaser.
This will allow people on ARM system to have native docker image of chproxy

Also switch setup-go actions to use go.mod version to avoid discrepancies

Thanks to @orian for reminding us that we forgot to enable this build

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

Checklist

• Linter passes correctly
• Add tests which fail without the change (if possible)
• All tests passing
• Extended the README / documentation, if necessary

Does this introduce a breaking change?

• Yes
• No

Further comments

This was tested on a private fork and separate docker image to make sure it works