Use correct format specifier

std::streamoff is signed on target platform.

src/logic/pakfile.cpp

@@ -522,7 +522,7 @@ static bool Pak_StreamToStreamEncode(BinaryIO& inStream, BinaryIO& outStream, co
 
 			if (ZSTD_isError(remaining))
 			{
-				Warning("Failed to compress frame at %zu to frame at %zu: [%s].\n",
+				Warning("Failed to compress frame at %zd to frame at %zd: [%s].\n",
 					inStream.TellGet(), outStream.TellPut(), ZSTD_getErrorName(remaining));
 
 				ZSTD_freeCCtx(cctx);