cellMusic: Fix shuffle always producing the same order

The shuffle in step_track() used std::default_random_engine with a
default (fixed) seed, causing the playlist to be 'shuffled' into the
same deterministic order every time. Use std::random_device to seed the
engine so each shuffle produces a genuinely random order.

Fixes #18672

rpcs3/Emu/Cell/Modules/cellMusicSelectionContext.cpp

@@ -362,7 +362,8 @@ u32 music_selection_context::step_track(bool next)
 		{
 			// We reached the first or last track again. Let's shuffle!
 			cellMusicSelectionContext.notice("step_track: Shuffling playlist...");
-			auto engine = std::default_random_engine{};
+			std::random_device rd;
+			auto engine = std::default_random_engine{rd()};
 			std::shuffle(std::begin(playlist), std::end(playlist), engine);
 		}
 	}