add python et install to ci

Author: metascroy

.github/workflows/pull.yml

@@ -1080,6 +1080,14 @@ jobs:
         run: |
           echo "Installing ExecuTorch"
           bash torchchat/utils/scripts/install_et.sh
+      - name: Install ExecuTorch python
+        run: |
+          echo "Install ExecuTorch python"
+          pushd et-build/src/executorch
+          chmod +x ./install_requirements.sh
+          chmod +x ./install_requirements.py
+          ./install_requirements.sh
+          popd
       - name: Install runner
         run: |
           echo "Installing runner"