Potential workaround for poor zstd performance

Performance is still not great, but better

internal/decompress/gzip.go

@@ -11,3 +11,9 @@ type GZip struct{}
 func (g GZip) Reader(src io.Reader) (io.ReadCloser, error) {
 	return zlib.NewReader(src)
 }
+
+func (g GZip) Resetable() bool { return true }
+
+func (g GZip) Reset(old, src io.Reader) error {
+	return old.(zlib.Resetter).Reset(src, nil)
+}