Add missing #include.

Add missing copyright.

test/test_module.cpp

@@ -1,3 +1,9 @@
+//  (C) John Maddock 2022.
+//  Use, modification and distribution are subject to the Boost Software License,
+//  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt).
+//
+//  See http://www.boost.org/libs/type_traits for most recent version including documentation.
 
 #include <complex>