using multi_gpu consistently (#8446)

* s|multiple_gpu|multi_gpu|g; s|multigpu|multi_gpu|g'

* doc

examples/seq2seq/test_seq2seq_examples_multi_gpu.py

@@ -8,7 +8,7 @@ from transformers.testing_utils import (
     execute_subprocess_async,
     get_gpu_count,
     require_torch_gpu,
-    require_torch_multigpu,
+    require_torch_multi_gpu,
     slow,
 )
 
@@ -21,8 +21,8 @@ class TestSummarizationDistillerMultiGPU(TestCasePlus):
     def setUpClass(cls):
         return cls
 
-    @require_torch_multigpu
-    def test_multigpu(self):
+    @require_torch_multi_gpu
+    def test_multi_gpu(self):
 
         updates = dict(
             no_teacher=True,