[MakefileConfigurator] Fix indentation of help target

[Kocal]

When working on symfony/recipes-contrib#1936, that contains a Makefile, I noticed that the Makefile boilerplate generated in 2.x (1.x not affected) contains 4 spaces instead of a tabulation in the task help.

With the spaces:

With the tabulation:

Note: I didn't tested the fix, I'm assuming it works 🤞🏻

[GromNaN]

The fix looks good! However, it's missing a test — none of the existing tests exercise the boilerplate creation path (they all touch the Makefile before calling configure()).

Here's a test to add to tests/Configurator/MakefileConfiguratorTest.php that would have caught the regression:

public function testConfigureCreatesBoilerplateWithTabIndentation()
{
    $configurator = new MakefileConfigurator(
        $this->getMockBuilder(Composer::class)->getMock(),
        $this->getMockBuilder(IOInterface::class)->getMock(),
        new Options(['root-dir' => FLEX_TEST_DIR])
    );
    $lock = $this->getMockBuilder(Lock::class)->disableOriginalConstructor()->getMock();

    $recipe = $this->getMockBuilder(Recipe::class)->disableOriginalConstructor()->getMock();
    $recipe->expects($this->any())->method('getName')->willReturn('FooBundle');

    $makefile = FLEX_TEST_DIR.'/Makefile';
    @unlink($makefile);

    $configurator->configure($recipe, ['foo: ## Do foo'], $lock);

    $this->assertFileExists($makefile);
    $contents = file_get_contents($makefile);
    $this->assertStringContainsString("ifndef APP_ENV\n    include .env\nendif", $contents);
    $this->assertStringContainsString('.DEFAULT_GOAL := help', $contents);
    $this->assertStringContainsString('.PHONY: help', $contents);
    $this->assertStringContainsString("help:\n\t@awk", $contents, 'The help target must use a tab for indentation, not spaces');
}

[Kocal]

Thank you @GromNaN ❤️

[Kocal]

Failing checks will be fixed by #1084