Fix onnx export CLI for transformers >= 4.45 (#2053)

* fix onnx export

* add test

optimum/exporters/onnx/convert.py

@@ -26,6 +26,7 @@
 
 import numpy as np
 import onnx
+from transformers.generation import GenerationMixin
 from transformers.modeling_utils import get_parameter_dtype
 from transformers.utils import is_tf_available, is_torch_available
 
@@ -1127,7 +1128,7 @@ def onnx_export_from_model(
 
         if check_if_transformers_greater("4.44.99"):
             misplaced_generation_parameters = model.config._get_non_default_generation_parameters()
-            if model.can_generate() and len(misplaced_generation_parameters) > 0:
+            if isinstance(model, GenerationMixin) and len(misplaced_generation_parameters) > 0:
                 logger.warning(
                     "Moving the following attributes in the config to the generation config: "
                     f"{misplaced_generation_parameters}. You are seeing this warning because you've set "

tests/exporters/onnx/test_exporters_onnx_cli.py

@@ -602,6 +602,14 @@ def test_diffusion(self):
                 check=True,
             )
 
+    def test_sentence_transformers(self):
+        with TemporaryDirectory() as tmpdirname:
+            subprocess.run(
+                f"python3 -m optimum.exporters.onnx --model sentence-transformers-testing/stsb-bert-tiny-onnx --task feature-extraction {tmpdirname}",
+                shell=True,
+                check=True,
+            )
+
     def test_legacy(self):
         with TemporaryDirectory() as tmpdirname:
             subprocess.run(