fix insufficient sh permissions

[canxin121]

Origin issue: fzyzcjy/flutter_rust_bridge#1840
Origin pr: fzyzcjy/flutter_rust_bridge#1842

Simple problem description: if you create a new flutter_rust project in windows, the sh script is automatically created, but the executable permissions cannot be set. When moving this project to macOS and executing flutter build ios to build ipa files the process crashes due to insufficient sh script permissions.

This permission problem can be circumvented by sh script.sh rather than script.sh

As verified by Github Action's macOS Runner, the modified cargokit works fine for building ipa apps using the flutter_rust project created on windows.

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[canxin121]

Now all tests runs well here: https://github.com/canxin121/todolist/actions/runs/8476136585
I've found that in android builds, run_build_tool.sh seems to be called directly outside of the gradle, and even if you use script.sh in the gradle, it still crashes due to permission issues. So I'm afraid that chmod is the most convenient solution

[canxin121]

@knopp Can you take a look at this

[knopp]

Thanks!