Update src/tests/libxrpl/basics/Mutex.cpp

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: kuznetsss

src/tests/libxrpl/basics/Mutex.cpp

@@ -6,6 +6,7 @@
 #include <shared_mutex>
 #include <string>
 #include <vector>
+#include <memory>
 
 using namespace xrpl;