Function set_GIT_DIRTY 

pub fn set_GIT_DIRTY() -> Result<(), String>

Sets the GIT_DIRTY env variable.

Call this from build.rs. Use env! in your main.rs to use the variable.

Sets the variable to "true" if the git repository contains uncommitted changes. Otherwise, sets it to "false".

Errors

Returns an error if it fails to execute the git command.