fix(gpt): drop deprecation usage of get_max_length()

Author: fumiama

ChatTTS/model/gpt.py

@@ -187,7 +187,10 @@ def _prepare_generation_inputs(
                     if cache_position is not None
                     else past_key_values.get_seq_length()
                 )
-                max_cache_length = past_key_values.get_max_length()
+                try:
+                    max_cache_length = past_key_values.get_max_cache_shape()
+                except:
+                    max_cache_length = past_key_values.get_max_length() # deprecated in transformers 4.48
                 cache_length = (
                     past_length
                     if max_cache_length is None