Update ci to dynamically set thread count for infection

Author: chapterjason

.github/workflows/ci.yml

@@ -100,6 +100,7 @@ jobs:
                     php-version: 8.4
                     tools: infection
             -   uses: ramsey/composer-install@v3
-            -   run: infection --min-msi=64 --min-covered-msi=70 --threads=4
+            -   run: |
+                    infection --min-msi=64 --min-covered-msi=70 "--threads=$(nproc)"
                 env:
                     STRYKER_DASHBOARD_API_KEY: ${{ secrets.STRYKER_DASHBOARD_API_KEY }}