Add `pyPath` option to allow setting different python executable

[protibimbok]

The plugin used to run

python manage.py 'arg1' 'arg2'

Now, there is an option to customize the python executable path.

export default defineConfig({
    plugins: [
        ...
        djangoVite({
            ...
            pyPath: './to/idk/python'
        })
    ],
});

This would result in running the following command:

./to/idk/python manage.py 'arg1' 'arg2'