[CI] Install stable torch/tv in docs when on release branch

ghstack-source-id: 7c39c049c7cff0ee112be2d07597f2e291d2fafd
Pull Request resolved: #2761

.github/workflows/docs.yml

@@ -76,10 +76,13 @@ jobs:
         git version
         
         # 5. Install PyTorch
-        python3 -m pip install --pre torch torchvision --index-url https://download.pytorch.org/whl/nightly/cpu -U --quiet --root-user-action=ignore
-        
-        # 6. Install tensordict
-        python3 -m pip install git+https://github.com/pytorch/tensordict.git --quiet --root-user-action=ignore
+        if [[ ${{ github.event_name }} == push && (${{ github.ref_type }} == tag || (${{ github.ref_type }} == branch && ${{ github.ref_name }} == release/*)) ]]; then
+          python3 -m pip install torch torchvision
+          python3 -m pip install tensordict
+        else
+          python3 -m pip install --pre torch torchvision --index-url https://download.pytorch.org/whl/nightly/cpu -U --quiet --root-user-action=ignore
+          python3 -m pip install git+https://github.com/pytorch/tensordict.git --quiet --root-user-action=ignore
+        fi
         
         # 7. Install TorchRL
         python3 setup.py develop