Use script-shell from npm config to run the package.json scripts

[iki]

It's a common practice on projects to use shell syntax in package.json scripts and developers on Windows use script-shell config in .npmrc:

script-shell=C:\Program Files\git\bin\bash.exe

or case-insensitive env:

npm_config_script_shell=C:\Program Files\git\bin\bash.exe 

Without that dum on Windows fails to run many scripts on our projects.

Willing to learn Rust and make a PR if you like :)