use auto with make_unique

C arrays can be used with make_unique in C++17.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/command/FileCommands.cxx

@@ -213,7 +213,7 @@ read_stream_art(Response &r, const std::string_view art_directory,
 		std::min<offset_type>(art_file_size - offset,
 				      r.GetClient().binary_limit);
 
-	std::unique_ptr<std::byte[]> buffer(new std::byte[buffer_size]);
+	auto buffer = std::make_unique<std::byte[]>(buffer_size);
 
 	std::size_t read_size = 0;
 	if (buffer_size > 0) {