The extended trainer tests should require torch (#12650)

tests/extended/test_trainer_ext.py

@@ -28,6 +28,7 @@ from transformers.testing_utils import (
     execute_subprocess_async,
     get_gpu_count,
     get_torch_dist_unique_port,
+    require_torch,
     require_torch_gpu,
     require_torch_multi_gpu,
     require_torch_non_multi_gpu,
@@ -69,6 +70,7 @@ def require_apex(test_case):
         return test_case
 
 
+@require_torch
 class TestTrainerExt(TestCasePlus):
     def run_seq2seq_quick(
         self,