Update nightly.yml

Author: opensource-krzysztof

.github/workflows/nightly.yml

@@ -48,6 +48,7 @@ jobs:
      run: vcpkg install --triplet x64-windows
 
    - name: Download and install win64devkit
+     shell: cmd
      run: |
        curl -L https://github.com/skeeto/w64devkit/releases/download/v2.2.0/w64devkit-x64-2.2.0.7z.exe --output w64devkit.zip
        Expand-Archive w64devkit.zip -DestinationPath .