FIX: Adjust transformers version check for bloom (#1992)

The fix to the bloom architecture was not actually released in
transformers 4.43.3, which makes the version check invalid. Instead, now
checking an attribute on the BloomPreTrainedModel.

src/peft/utils/constants.py

@@ -12,9 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import packaging.version
 import torch
-import transformers
+from transformers import BloomPreTrainedModel
 
 
 # needed for prefix-tuning of bloom model
@@ -46,9 +45,10 @@ def starcoder_model_postprocess_past_key_value(past_key_values):
     "gpt_bigcode": starcoder_model_postprocess_past_key_value,
 }
 
-if packaging.version.parse(transformers.__version__) <= packaging.version.parse("4.43.3"):
+if hasattr(BloomPreTrainedModel, "_convert_to_standard_cache"):
     # special handling for bloom architecture was fixed in:
     # https://github.com/huggingface/transformers/pull/31445
+    # the _convert_to_standard_cache method is removed in the PR and thus serves as an indicator
     TRANSFORMERS_MODELS_TO_PREFIX_TUNING_POSTPROCESS_MAPPING["bloom"] = bloom_model_postprocess_past_key_value
 
 TRANSFORMERS_MODELS_TO_LNTUNING_TARGET_MODULES_MAPPING = {