clean up disk space in gh action script

.github/workflows/main.yaml

@@ -46,6 +46,14 @@ jobs:
             - name: Build Contracts
               run: make build
 
+            - name: Clean up disk space
+              run: |
+                  docker system prune -af
+                  docker volume prune -f
+                  sudo apt-get clean
+                  sudo rm -rf /var/log/*.log
+                  df -h
+
             - name: Compilation
               run: |
                   cd testing