[conex] Add a missing #include statements

See https://github.com/ToyotaResearchInstitute/conex/pull/4

--- conex/debug_macros.h
+++ conex/debug_macros.h
@@ -1,4 +1,6 @@
 #pragma once
+#include <array>
+#include <cassert>
 #include <chrono>
 #include <iomanip>
 #include <iostream>
