Unpin transformers version (#5650)

Reverts changes in #5629 after fixes have been applied to MII repo/MII
tests.

---------

Co-authored-by: Heyang Qin <heyangqin@microsoft.com>

.github/workflows/nv-mii.yml

@@ -46,7 +46,7 @@ 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 bdf36dc
+          # git checkout bdf36dc
           git rev-parse --short HEAD
           pip install .