Fix faking response metadata

src/Testing/Responses/Concerns/Fakeable.php

@@ -35,12 +35,8 @@ private static function buildAttributes(array $original, array $override): array
             unset($override[$key]);
         }
 
-        // we are going to append all remaining overrides with numeric keys
+        // we are going to append all remaining overrides
         foreach ($override as $key => $value) {
-            if (! is_numeric($key)) {
-                continue;
-            }
-
             $new[$key] = $value;
         }
 

tests/Responses/Assistants/AssistantResponse.php

@@ -46,8 +46,13 @@
 test('fake with override', function () {
     $response = AssistantResponse::fake([
         'id' => 'asst_1234',
+        'metadata' => [
+            'key' => 'value',
+        ],
     ]);
 
     expect($response)
-        ->id->toBe('asst_1234');
+        ->id->toBe('asst_1234')
+        ->metadata->toBeArray()
+        ->metadata->key->toBe('value');
 });