Add parallel command

Author: mttsch

.github/workflows/unit-tests.yml

@@ -42,6 +42,11 @@ jobs:
     runs-on: ubuntu-24.04
 
     steps:
+      - name: Install Act dependencies
+        if: ${{ env.ACT }}
+        run: |
+          apt-get update && apt-get install parallel -y
+
       - name: Checkout
         uses: https://github.com/actions/checkout@v4
         with: