Replaced get_max_length with get_max_cache_shape

get_max_length has been deprecated, and get_max_cache_shape should be used instead

modeling_hymba.py

@@ -2573,7 +2573,7 @@ class HymbaForCausalLM(HymbaPreTrainedModel):
             if isinstance(past_key_values, Cache):
                 cache_length = past_key_values.get_seq_length()
                 past_length = past_key_values.seen_tokens
-                max_cache_length = past_key_values.get_max_length()
+                max_cache_length = past_key_values.get_max_cache_shape()
 
                 past_length = cache_length