Remove pin from transformers version and fix Processing/Threading iss…

…ues in tests (#6822)

Changes from huggingface/transformers#34966
caused the `nv-torch-latest-v100` tests to fail with the following
error:

```
  File "/tmp/azureml/cr/j/e4bfd57a509846d6bbc4914639ad248d/exe/wd/actions-runner/_work/DeepSpeed/DeepSpeed/unit-test-venv/lib/python3.10/site-packages/transformers/modeling_utils.py", line 3941, in from_pretrained
    raise EnvironmentError(
OSError: Can't load the model for 'hf-internal-testing/tiny-random-VisionEncoderDecoderModel-vit-gpt2'. If you were trying to load it from 'https://huggingface.co/models', make sure you don't have a local directory with the same name. Otherwise, make sure 'hf-internal-testing/tiny-random-VisionEncoderDecoderModel-vit-gpt2' is the correct path to a directory containing a file named pytorch_model.bin, tf_model.h5, model.ckpt or flax_model.msgpack.
```

Sample failure here:
https://github.com/microsoft/DeepSpeed/actions/runs/12169422174/job/33942348835?pr=6794#step:8:3506

This was resolved on the Transformers side here:
huggingface/transformers#35236

.github/workflows/cpu-torch-latest.yml

@@ -42,7 +42,7 @@ jobs:
           git clone https://github.com/huggingface/transformers
           cd transformers
           # if needed switch to the last known good SHA until transformers@master is fixed
-          git checkout 6c3f168b3
+          # git checkout 6c3f168b3
           git rev-parse --short HEAD
           pip install .
 

.github/workflows/nv-torch-latest-v100.yml

@@ -38,7 +38,7 @@ jobs:
           git clone https://github.com/huggingface/transformers
           cd transformers
           # if needed switch to the last known good SHA until transformers@master is fixed
-          git checkout 6c3f168b3
+          # git checkout 6c3f168b3
           git rev-parse --short HEAD
           pip install .
 

.github/workflows/nv-torch-nightly-v100.yml

@@ -37,7 +37,7 @@ jobs:
           git clone https://github.com/huggingface/transformers
           cd transformers
           # if needed switch to the last known good SHA until transformers@master is fixed
-          git checkout 6c3f168b3
+          # git checkout 6c3f168b3
           git rev-parse --short HEAD
           pip install .