[9.x] Accept attribute to touch

[freekmurze]

With the changes in this PR you can replace this code...

$this->update(['attribute' => now()]);

... with ...

$this->touch('attribute');

Which feels a tad nicer.

I didn't find any test around the normal behaviour of touch so I didn't add any.

If you want to accept this PR, but want tests, point me where these should be created.

[gocanto]

what would it happen if a given model does not use timestamp? - wouldn't the guard ! $this->usesTimestamps() be necessary for this use case too?

[crynobone]

That should be covered by Line 30. This line covers $model->touch('custom_attribute'); and should affect usesTimestamps().

[johanrosenson]

usesTimestamps() only tells you if the Model is using the standard updated_at and created_at, so it should not be checked when $attribute is passed to the touch method.

It is valid to disable the updated/created timestamps (via $timestamps = false) but still use your own custom timestamp column for some other use case, which is when the $attribute argument would be used.