This is needed because the project does not have a `go.mod` file and
gets sent to go 1.16 semantics whenever it's imported by another project
and `any` doesn't exist in go 1.16, but the linter requires us to use
`any` here.
Setting the `go:build` tag forces the per-file language to the go
version specified.
Signed-off-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>