Bump for GB v0.4.0
Bump for GB v0.4.0

heroku/heroku-buildpack-go,cloudfoundry/go-buildpack,enkoder/heroku-buildpack-go,cloudfoundry/go-buildpack,michael-go/heroku-buildpack-go,michael-go/heroku-buildpack-go,titanous/heroku-buildpack-go,heroku/heroku-buildpack-go,cloudfoundry/go-buildpack