refactor(StandaloneMariadb): add type hint for destination method to improve code clarity

app/Models/StandaloneMariadb.php

@@ -4,6 +4,7 @@ namespace App\Models;
 
 use Illuminate\Database\Eloquent\Casts\Attribute;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Relations\MorphTo;
 use Illuminate\Database\Eloquent\SoftDeletes;
 
 class StandaloneMariadb extends BaseModel
@@ -253,7 +254,7 @@ class StandaloneMariadb extends BaseModel
         return $this->morphMany(LocalFileVolume::class, 'resource');
     }
 
-    public function destination()
+    public function destination(): MorphTo
     {
         return $this->morphTo();
     }