Fix test regression caused by node fixing CVE-2024-27980

[ntkme]

This is mainly a test-only fix:

• sass-embedded >=1.59.2 is not affected because in production release we always launch the dart.exe directly since this commit: 3088620
• sass-embedded <1.59.2 would be broken if a windows user upgrades to the latest node with the fix for the CVE. There is no security risk for sass-embedded itself even if a windows user uses a vulnerable version of node, because we don't have any arguments when launching .bat, thus there is no risk of injection with in this project. However, there might be attack factors in other node dependencies, therefore, it is recommended for windows users to upgrade to latest node and sass-embedded >=1.59.2.
• Test is broken because we use the .bat wrapper in the test, this is now blocked with the CVE fix. This PR fixes this case by adding shell: true.