Check config before skipping

[dhaarbrink]

This adds a check on the 'use_grumphp_paths' config before skipping so this task runs even though there are no changed files when use_grumphp_paths is set to false.

Q	A
Branch	master for features and deprecations
Bug fix?	yes
New feature?	no
BC breaks?	yes
Deprecations?	no
Documented?	no
Fixed tickets	-

New Task Checklist:

• Are the dependencies added to the composer.json suggestions?
• Is the doc/tasks.md file updated?
• Are the task parameters documented?
• Is the task registered in the tasks.yml file?
• Does the task contains phpunit tests?
• Is the configuration having logical allowed types?
• Does the task run in the correct context?
• Is the run() method readable?
• Is the run() method using the configuration correctly?
• Are all CI services returning green?

[veewee]

Thanks for the PR! It makes sense to do it like this.

Can you also add a unit test covering this case?
There is already a test for when there are files available, so it should be a small addition:
https://github.com/phpro/grumphp/blob/master/test/Unit/Task/PhpStanTest.php#L192

[Landerstraeten]

@veewee Can you check if I have added the correct unit test?

[Landerstraeten]

@dhaarbrink Thank you!