Update build.yml

Author: antonym

.github/workflows/build.yml

@@ -59,7 +59,7 @@ jobs:
         mkdir -p out
         wget https://github.com/linuxkit/linuxkit/releases/download/v1.2.0/linuxkit-linux-amd64
         chmod +x linuxkit-linux-amd64
-        ./linuxkit-linux-amd64 build -format kernel+initrd -name core -dir out core.yml
+        ./linuxkit-linux-amd64 build --format kernel+initrd --name core --dir out core.yml
     - name: Generate pre-release
       uses: "marvinpinto/action-automatic-releases@latest"
       with: