go.mod: update deps

[broady]

go.opencensus.io@v0.19.1 still depends on very old versions of Google APIs, resulting in an eventual import of "github.com/golang/lint". See googleapis/google-cloud-go#1359 and golang/lint#436 for background.

go.opencensus.io@v0.19.1 google.golang.org/genproto@v0.0.0-20181219182458-5a97ab628bfb
go.opencensus.io@v0.19.1 cloud.google.com/go@v0.34.0
go.opencensus.io@v0.19.1 google.golang.org/api@v0.0.0-20181220000619-583d854617af

google.golang.org/api is on v0.2.0
cloud.google.com/go is on v0.37.0

google.golang.org/grpc is on v0.19.0

/cc @jadekler

[bogdandrutu]

Trying to do the update in #1052 but cannot pass on windows. Any idea? Otherwise we may disable appveyor for the moment.

[dmitshur]

There's been progress made in #1052 by dropping the google.golang.org/genproto@v0.0.0-20181219182458-5a97ab628bfb module, which was causing trouble. But it seems more needs to be done before one can safely do go get -u on this module.

Consider that the latest go.mod of this module has:

opencensus-go/go.mod

Line 11 in 3b8e272

google.golang.org/api v0.2.0

Yet that module version has a problem where it requires go.opencensus.io@v0.19.1, see googleapis/google-api-go-client#342.

It seems some coordination will need to happen to resolve the circular problem.