Refactor to use only gopkg.in/yaml.v3

[alexandear]

Description

The PR removes usage of the package gopkg.in/yaml.v2 because the project already imports the newest gopkg.in/yaml.v3. There is no need to have both packages for marshaling YAML.

encoder.SetIndent(2) is used to comply with the behaviour of yaml.v2. yaml.v3 by default sets indentation to 4.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Refactoring

Version of Go used when building/testing:

• 1.22
• 1.23

How Has This Been Tested?

Run unit tests.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes