Fix issue where \Eloquent is not included when using write_mixin (#1352)

* Check for exact mixin name when writing

* changelog

* add mixin to test class

Co-authored-by: Barry vd. Heuvel <[email protected]>

tests/Console/ModelsCommand/GeneratePhpdocWithMixin/Models/Post.php

@@ -9,6 +9,7 @@ use Illuminate\Database\Eloquent\Model;
 /**
  * @property $someProp
  * @method someMethod(string $method)
+ * @mixin IdeHelperPost
  */
 class Post extends Model
 {