fix(create_dummy_models): skip primitive attributes ending in _config in _get_exact_config

PR #45333 added `serialize_explicit_per_layer_config: bool = False` to
PreTrainedConfig base class. Its name ends in `_config`, so the dir()
scan in `_get_exact_config` picks it up and tries to recurse into the
`False` value, crashing with `AttributeError: 'bool' object has no
attribute 'to_dict'` (affects Qwen3_5Config and any other config that
inherits the attribute).

Skip any sub_config that is neither a dict nor has a `to_dict` method,
i.e. plain primitives that happen to have a `_config`-suffixed name.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ydshieh

utils/create_dummy_models.py

@@ -543,6 +543,10 @@ def _get_exact_config(_config, config_class):
     for key in keys:
         sub_config = getattr(_config, key) if not isinstance(_config, dict) else _config[key]
         if sub_config is not None:
+            # Skip primitives (bool, int, str, …) that happen to have a name ending in `_config`
+            # (e.g. `serialize_explicit_per_layer_config` on PreTrainedConfig is a bool).
+            if not (isinstance(sub_config, dict) or hasattr(sub_config, "to_dict")):
+                continue
             # TODO: `VibeVoiceAcousticTokenizerEncoder/DecoderConfig` needs some protection!!!
             if sub_config.__class__ == _config.__class__:
                 continue