Force upgrade.

Author: carmocca

.azure/gpu-tests.yml

@@ -73,6 +73,7 @@ jobs:
         CUDA_VERSION_MM=$(python -c "import torch ; print(''.join(map(str, torch.version.cuda.split('.')[:2])))")
         pip install "bagua-cuda$CUDA_VERSION_MM>=0.9.0"
         pip install -e .[strategies]
+        pip install deepspeed==0.6.4  # TODO: remove when docker images are upgraded
         pip install --requirement requirements/pytorch/devel.txt
         pip list
       env: