ci: twister: install Python dependencies in twister-build step

This ensures we catch up on latest requirements in case Docker image is
lagging behind.

Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>

.github/workflows/twister.yaml

@@ -210,6 +210,10 @@ jobs:
           echo "github.base_ref: ${{ github.base_ref }}"
           echo "github.ref_name: ${{ github.ref_name }}"
 
+      - name: Install Python packages
+        run: |
+          pip install -r scripts/requirements-actions.txt --require-hashes
+
       - name: Set up ccache
         run: |
           mkdir -p ${CCACHE_DIR}