CI: non-remote GH Actions now use a python venv (#16789)

.github/workflows/update_metdata.yml

@@ -16,17 +16,19 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - name: Loading cache.
+      - name: Load cached virtual environment
         uses: actions/cache@v2
         id: cache
         with:
-          path: ~/.cache/pip
-          key: v1-metadata-${{ hashFiles('setup.py') }}
+          path: ~/venv/
+          key: v2-metadata-${{ hashFiles('setup.py') }}
 
       - name: Setup environment
         run: |
+          . ~/venv/bin/activate
           pip install git+https://github.com/huggingface/transformers#egg=transformers[dev]
 
       - name: Update metadata
         run: |
+          . ~/venv/bin/activate
           python utils/update_metadata.py --token ${{ secrets.SYLVAIN_HF_TOKEN }} --commit_sha ${{ github.sha }}