build: use yaml/go-yaml instead of unmaintained yaml.v3, fixes #7280

[rfay]

The Issue

• #7280

yaml/go-yaml seems to have reached some kind of maturity

How This PR Solves The Issue

Try it out.

Manual Testing Instructions

Look at test results. Use it. Tests should tell us everything.

Automated Testing Overview

Release/Deployment Notes

[github-actions[bot]]

Download the artifacts for this pull request:

• all-ddev-executables.zip
• ddev-macos-amd64.zip
• ddev-macos-arm64.zip
• ddev-linux-arm64.zip
• ddev-linux-amd64.zip
• ddev-windows-amd64.zip
• ddev-windows-amd64-installer.zip
• ddev-windows-arm64.zip
• ddev-windows-arm64-installer.zip

See Testing a PR.

[rfay]

Updated mergo to lose its dependency.

The traditional module is still required by stretchr/testify, which is used in testcommon tests (assert)

$ go mod why gopkg.in/yaml.v3
# gopkg.in/yaml.v3
github.com/ddev/ddev/pkg/testcommon
github.com/stretchr/testify/assert
github.com/stretchr/testify/assert/yaml
gopkg.in/yaml.v3

• https://github.com/stretchr/testify/issues/1724