stats package migration

[codebien]

k6 v0.38.0 has been released and it contains a breaking change for the stats package. We merged it in the metrics package. The current build of the extension could be affected.

• The fix should migrate all the references of the stats package to the relative metrics definition. The API is not changed so it should be just a find and replace of the package.
• An upgrade of the k6's go module to v0.38.0 is required.
• A migration to the new module API could be also required info and context are available here https://k6.io/docs/extensions/guides/create-an-extension/#advanced-javascript-extension.

[pmalhaire]

@codebien The migration is in wip in https://github.com/pmalhaire/xk6-mqtt/tree/update/0.38.0

[pmalhaire]

@codebien migration is done, between I am not sure stats are done the right way

    state := m.vu.State()
    msgByteLen := len([]byte(message))
    state.BuiltinMetrics.DataSent.Sink.Add(
        metrics.Sample{Metric: &metrics.Metric{}, Value: float64(msgByteLen), Time: time.Now()},
    )

[pmalhaire]

Update done