command/player, SongPrint: use AudioFormatFormatter()

libfmt version 10 apparently doesn't know how to format a
`StringBuffer`, failing the MPD build.  Since we have a formatter
specialization for `AudioFormat`, let's use that - it's better and
easier to use.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1807

src/command/PlayerCommands.cxx

@@ -13,6 +13,7 @@
 #include "Partition.hxx"
 #include "Instance.hxx"
 #include "IdleFlags.hxx"
+#include "lib/fmt/AudioFormatFormatter.hxx"
 #include "util/StringBuffer.hxx"
 #include "util/ScopeExit.hxx"
 #include "util/Exception.hxx"
@@ -170,7 +171,7 @@ handle_status(Client &client, [[maybe_unused]] Request args, Response &r)
 
 		if (player_status.audio_format.IsDefined())
 			r.Fmt(FMT_STRING(COMMAND_STATUS_AUDIO ": {}\n"),
-			      ToString(player_status.audio_format));
+			      player_status.audio_format);
 	}
 
 #ifdef ENABLE_DATABASE