Add missing header.

Protobuf 22.x no longer pulls in <set>, it needs to be
included explicitly.

Bug: 329747255
Test: presubmit
Change-Id: I8c0b219322b10a655d5687c506d1047ddb8aa99e
diff --git a/services/surfaceflinger/Tracing/TransactionTracing.h b/services/surfaceflinger/Tracing/TransactionTracing.h
index ddbf3e4..cb96e05 100644
--- a/services/surfaceflinger/Tracing/TransactionTracing.h
+++ b/services/surfaceflinger/Tracing/TransactionTracing.h
@@ -24,6 +24,7 @@
 
 #include <mutex>
 #include <optional>
+#include <set>
 #include <thread>
 
 #include "FrontEnd/DisplayInfo.h"