Don't include not-needed memory header.

verible/verilog/CST/class_test.cc

diff --git a/verible/verilog/CST/class_test.cc b/verible/verilog/CST/class_test.cc
index 6aeb525..b01413f 100644
--- a/verible/verilog/CST/class_test.cc
+++ b/verible/verilog/CST/class_test.cc
@@ -22,7 +22,6 @@
 
 #include "verible/verilog/CST/class.h"
 
-#include <memory>
 #include <string_view>
 #include <vector>
 

verible/verilog/CST/module_test.cc

diff --git a/verible/verilog/CST/module_test.cc b/verible/verilog/CST/module_test.cc
index f8dd57b..0d26498 100644
--- a/verible/verilog/CST/module_test.cc
+++ b/verible/verilog/CST/module_test.cc
@@ -22,7 +22,6 @@
 
 #include "verible/verilog/CST/module.h"
 
-#include <memory>
 #include <vector>
 
 #include "absl/log/die_if_null.h"