_content/blog/execution-traces-2024: fix compilation error

The `id` variable is not used, and there's no `GoroutineTransition`
method, it's just called `Goroutine`.

Change-Id: Ib3d3adf55542976c40274a7458fe6931853c495c
Reviewed-on: https://go-review.googlesource.com/c/website/+/576055
Reviewed-by: Felix Geisendörfer <felix.geisendoerfer@datadoghq.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
diff --git a/_content/blog/execution-traces-2024/reader.go b/_content/blog/execution-traces-2024/reader.go
index 7fdf7cb..5e90c59 100644
--- a/_content/blog/execution-traces-2024/reader.go
+++ b/_content/blog/execution-traces-2024/reader.go
@@ -35,8 +35,7 @@
 		if ev.Kind() == trace.EventStateTransition {
 			st := ev.StateTransition()
 			if st.Resource.Kind == trace.ResourceGoroutine {
-				id := st.Resource.Goroutine()
-				from, to := st.GoroutineTransition()
+				from, to := st.Goroutine()
 
 				// Look for goroutines blocking, and count them.
 				if from.Executing() && to == trace.GoWaiting {