Update repo to isort v5 (#6686)

* Run new isort

* More changes

* Update CI, CONTRIBUTING and benchmarks

tests/test_modeling_tf_openai.py

@@ -25,11 +25,12 @@ from .test_modeling_tf_common import TFModelTesterMixin, ids_tensor
 
 if is_tf_available():
     import tensorflow as tf
+
     from transformers.modeling_tf_openai import (
-        TFOpenAIGPTModel,
-        TFOpenAIGPTLMHeadModel,
-        TFOpenAIGPTDoubleHeadsModel,
         TF_OPENAI_GPT_PRETRAINED_MODEL_ARCHIVE_LIST,
+        TFOpenAIGPTDoubleHeadsModel,
+        TFOpenAIGPTLMHeadModel,
+        TFOpenAIGPTModel,
     )