ci: add build step

Author: ZCShou

.github/workflows/test-qemu.yml

@@ -48,6 +48,11 @@ jobs:
             echo "Updated kernel_path in $config"
           done
 
+      - name: Build axvisor
+        run: |
+          cargo xtask defconfig qemu-aarch64 \
+          cargo xtask build
+
       - name: Run tests
         run: |
           export RUST_LOG=debug