Repository: Lightning-Universe/lightning-transformers (language: python)

Issue:
PL has changed the paramerters of Trainer
## 🐛 Bug

In the latest pytorch-lightning ( 1.6.x ), the argument of number of gpus has changed to 'devices', but in this project's requirement it's 
`pytorch-lightning>=1.4.0`. So pip will automatically install 1.6.x which conflicts to the config file


Discussion / hints:
@ElderWanng mind sending a PR? :rabbit: 
@ElderWanng if you are not working on it, I want to make a PR
cc @Borda  
> if you are not working on it, I want to make a PR

that would be great!
@Borda I am preparing the PR, I have some confusions, 

1. `pl.Trainer` still has the argument `gpus`, so should I keep it along side with argument `devices`, also I have seen some benchmark config files which contains `gpus` should I change those?

2. Also in the main `README.md` there are several commands which can be changed, like from - 
`python train.py task=nlp/language_modeling dataset=nlp/language_modeling/wikitext trainer.gpus=1 training.batch_size=8` to `python train.py task=nlp/language_modeling dataset=nlp/language_modeling/wikitext trainer.accelerator=gpu training.batch_size=8` we don't need to manually set `devices` if we set the accelerator, correct me if I am wrong. 

Let me know your opinion. 

Fix patch:
diff --git a/conf/trainer/benchmark.yaml b/conf/trainer/benchmark.yaml
index e5106ce1..dace23d3 100644
--- a/conf/trainer/benchmark.yaml
+++ b/conf/trainer/benchmark.yaml
@@ -1,6 +1,6 @@
 defaults:
   - default # add args from default trainer conf
-gpus: 1
+devices: 1
 accelerator: ddp
 precision: 16
 checkpoint_callback: False
diff --git a/conf/trainer/default.yaml b/conf/trainer/default.yaml
index 4ff57ccd..4a875b6c 100644
--- a/conf/trainer/default.yaml
+++ b/conf/trainer/default.yaml
@@ -7,7 +7,7 @@ gradient_clip_val: 0.0
 process_position: 0
 num_nodes: 1
 num_processes: 1
-gpus: null
+devices: null
 auto_select_gpus: False
 tpu_cores: null
 log_gpu_memory: null


Test patch:
diff --git a/tests/core/test_callbacks.py b/tests/core/test_callbacks.py
index 886a3e0d..c978be6a 100644
--- a/tests/core/test_callbacks.py
+++ b/tests/core/test_callbacks.py
@@ -78,7 +78,7 @@ def test_training_steps(max_epochs, num_processes, limit_train_batches, modifier
         num_processes=num_processes,
         limit_train_batches=limit_train_batches,
         logger=WABLogger(offline=True),
-        gpus=0,
+        devices=0,
     )
 
     trainer.fit(model, data_module)