Fix missing function issue (#711)

* Fix missing function issue

`getUnqualifiedScoutKeyName` doesn't exist anymore. Since `getScoutKeyName` sends back to `\Illuminate\Database\Eloquent\Model::getKeyName` which is unqualified, the fix is straightforward.

* Update MeilisearchEngineTest.php

Author: JerryBels

src/Engines/MeilisearchEngine.php

@@ -248,7 +248,7 @@ public function mapIdsFrom($results, $key)
      */
     public function keys(Builder $builder)
     {
-        $scoutKey = $builder->model->getUnqualifiedScoutKeyName();
+        $scoutKey = $builder->model->getScoutKeyName();
 
         return $this->mapIdsFrom($this->search($builder), $scoutKey);
     }

tests/Unit/MeilisearchEngineTest.php

@@ -242,7 +242,7 @@ public function test_returns_primary_keys_when_custom_array_order_present()
         $builder = m::mock(Builder::class);
 
         $model = m::mock(stdClass::class);
-        $model->shouldReceive(['getUnqualifiedScoutKeyName' => 'custom_key']);
+        $model->shouldReceive(['getScoutKeyName' => 'custom_key']);
         $builder->model = $model;
 
         $engine->shouldReceive('keys')->passthru();