CI: Add build step

Author: felsenhower

.github/workflows/correctness_check.yaml

@@ -12,6 +12,9 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
+      - name: Build partdiff
+        run: make
+
       - name: Install Valgrind
         run: sudo apt-get update && sudo apt-get install -y valgrind