GitHub workflow C++ build: Install DejaGNU (as root)

Author: jokalode

.github/workflows/cpp.yaml

@@ -15,7 +15,7 @@ jobs:
     steps:
     - uses: actions/checkout@v3
     - name: Install DejaGNU
-      run: apt-get install dejagnu
+      run: sudo apt-get install dejagnu
     - name: Initialize GNU build system
       run: |
         autoreconf -f -i -s