add zstd module

Author: fairingrey

src/stream/mod.rs

@@ -13,6 +13,7 @@ mod deflate;
 mod flate;
 mod gzip;
 mod zlib;
+mod zstd;
 
 pub use brotli::{BrotliDecoder, BrotliEncoder};
 pub use deflate::{DeflateDecoder, DeflateEncoder};