Revert "Update neqo-transport/src/qlog.rs"

This reverts commit cf986bb.

`as_millis_f32` is nightly experimental.

neqo-transport/src/qlog.rs

@@ -340,7 +340,7 @@ pub fn metrics_updated(qlog: &NeqoQlog, updated_metrics: &[QlogMetric]) {
                 QlogMetric::MinRtt(v) => min_rtt = Some(v.as_secs_f32() * 1000.0),
                 QlogMetric::SmoothedRtt(v) => smoothed_rtt = Some(v.as_secs_f32() * 1000.0),
                 QlogMetric::LatestRtt(v) => latest_rtt = Some(v.as_secs_f32() * 1000.0),
-                QlogMetric::RttVariance(v) => rtt_variance = Some(v.as_millis_f32()),
+                QlogMetric::RttVariance(v) => rtt_variance = Some(v.as_secs_f32() * 1000.0),
                 QlogMetric::PtoCount(v) => pto_count = Some(u16::try_from(*v).unwrap()),
                 QlogMetric::CongestionWindow(v) => {
                     congestion_window = Some(u64::try_from(*v).unwrap());