Update go-yaml dependency.

go.mod

go.sum

server/config.go

vendor/github.com/go-yaml/yaml/.travis.yml

vendor/github.com/go-yaml/yaml/LICENSE

vendor/github.com/go-yaml/yaml/LICENSE.libyaml

vendor/github.com/go-yaml/yaml/NOTICE

vendor/github.com/go-yaml/yaml/README.md

vendor/github.com/go-yaml/yaml/apic.go

vendor/github.com/go-yaml/yaml/decode.go

vendor/github.com/go-yaml/yaml/emitterc.go

vendor/github.com/go-yaml/yaml/encode.go

vendor/github.com/go-yaml/yaml/parserc.go

vendor/github.com/go-yaml/yaml/readerc.go

vendor/github.com/go-yaml/yaml/resolve.go

vendor/github.com/go-yaml/yaml/scannerc.go

vendor/github.com/go-yaml/yaml/sorter.go

vendor/github.com/go-yaml/yaml/writerc.go

vendor/github.com/go-yaml/yaml/yaml.go

vendor/github.com/go-yaml/yaml/yamlh.go