fix(dsp): AWS::max_new_token is redundant to LM::max_tokens

Setting max_new_token did not work to increase generated token number
for Antropic, but max_tokens does.

According to:
https://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-anthropic-claude-messages.html
max_tokens is the correct parameter

Author: sysid

dsp/modules/aws_models.py

@@ -49,6 +49,9 @@ def __init__(
         self._max_context_size: int = max_context_size
         self._max_new_tokens: int = max_new_tokens
 
+        # make it consistent with equivalent LM::max_token
+        self.kwargs["max_tokens"] = max_new_tokens
+
         self.kwargs = {
             **self.kwargs,
             **kwargs,
@@ -63,7 +66,7 @@ def _call_model(self, body: str) -> str | list[str]:
         """Call model, get generated input without the formatted prompt."""
 
     def _estimate_tokens(self, text: str) -> int:
-        return len(text)/CHARS2TOKENS
+        return len(text) / CHARS2TOKENS
 
     def _extract_input_parameters(
         self,