Use buildkite/yaml to enable anchors in stages

[jbrockopp]

Directly in relation to:

go-yaml/yaml#184

The solution to use buildkite/yaml is documented in the thread.

NOTE:

We vendor directly from the commit:

(0caa5f0796e36057e59d6782832a9c774f457842)

rather then the release:

(v2.2.0)

because of a Go module versioning issue:

https://github.com/golang/go/wiki/Modules#semantic-import-versioning

If the module is version v2 or higher, the major version of the module must be included as a /vN at the end of the module paths used in go.mod files (e.g., module github.com/my/mod/v2, require github.com/my/mod/v2 v2.0.1) and in the package import path (e.g., import "github.com/my/mod/v2/mypkg"). This includes the paths used in go get commands (e.g., go get github.com/my/mod/[email protected]. Note there is both a /v2 and a @v2.0.1 in that example. One way to think about it is that the module name now includes the /v2, so include /v2 whenever you are using the module name).

$ go get -u github.com/buildkite/[email protected]
go: finding github.com/buildkite/yaml v2.2.0
go: finding github.com/buildkite/yaml v2.2.0
go get github.com/buildkite/[email protected]: github.com/buildkite/[email protected]: invalid version: module contains a go.mod file, so major version must be compatible: should be v0 or v1, not v2

[kneal]

LGTM 🐬

[KellyMerrick]

lgtm