add config for mamba 2.8b model parameter (#1946)

* first commit

* Make the mamba config public.

---------

Co-authored-by: laurent <laurent.mazare@gmail.com>

candle-transformers/src/models/mamba.rs

@@ -10,10 +10,10 @@ const D_STATE: usize = 16;
 
 #[derive(Debug, Clone, serde::Deserialize)]
 pub struct Config {
-    d_model: usize,
-    n_layer: usize,
-    vocab_size: usize,
-    pad_vocab_size_multiple: usize,
+    pub d_model: usize,
+    pub n_layer: usize,
+    pub vocab_size: usize,
+    pub pad_vocab_size_multiple: usize,
 }
 
 impl Config {