fix(page): do not update CreatedBy prop (#251)

Closes #249

src/Pages/Client.php

@@ -5,6 +5,7 @@
 use Notion\Blocks\BlockInterface;
 use Notion\Configuration;
 use Notion\Infrastructure\Http;
+use Notion\Pages\Properties\CreatedBy;
 use Notion\Pages\Properties\CreatedTime;
 use Notion\Pages\Properties\LastEditedBy;
 use Notion\Pages\Properties\LastEditedTime;
@@ -61,7 +62,7 @@ public function create(Page $page, array $content = []): Page
     public function update(Page $page): Page
     {
         $updatableProps = array_filter($page->properties, function (PropertyInterface $p) {
-            $notUpdatableProps = [ CreatedTime::class, LastEditedBy::class, LastEditedTime::class ];
+            $notUpdatableProps = [ CreatedTime::class, LastEditedBy::class, LastEditedTime::class, CreatedBy::class ];
 
             return (!in_array($p::class, $notUpdatableProps));
         });