`gcc-12` cleaned up implicit header includes and now requires
explicit '<memory>' for 'std::unique_ptr<>':
openmpt123/openmpt123.cpp:194:14: error: 'unique_ptr' in namespace 'std' does not name a template type
194 | std::unique_ptr<file_audio_stream_base> impl;
| ^~~~~~~~~~
openmpt123/openmpt123.cpp:109:1: note: 'std::unique_ptr' is defined in header '<memory>'; did you forget to '#include <memory>'?
108 | #include "openmpt123_waveout.hpp"
+++ |+#include <memory>
109 |
