Take a tick a little early as the network look's tick

The liveness loop's ticker drifts; a look skipped for a few milliseconds
would wait a whole further tick.

internal/network/network.go

@@ -199,7 +199,8 @@ func (j *Judge) Look(ctx context.Context) (Statement, bool) {
 	j.mu.Lock()
 	defer j.mu.Unlock()
 	now := j.m.Now()
-	if !j.lookedAt.IsZero() && now.Sub(j.lookedAt) < LookEvery {
+	// A tick a little early is still the tick: the loop that calls this runs on its own clock.
+	if !j.lookedAt.IsZero() && now.Sub(j.lookedAt) < LookEvery-LookEvery/10 {
 		return j.said, false
 	}
 	j.lookedAt = now