```

feat: add __call__ in field_serializer and update body wait logic

- In g4f/client/stubs.py, add a __call__ method to the field_serializer class that returns the first positional argument.
- In g4f/requests/__init__.py, replace the wait_for call with a while loop that repeatedly evaluates "document.querySelector('body:not(.no-js)')" and sleeps until the element is found.
```

g4f/client/stubs.py

@@ -22,6 +22,8 @@ except ImportError:
     class field_serializer():
         def __init__(self, field_name):
             self.field_name = field_name
+        def __call__(self, *args, **kwargs):
+            return args[0]
 
 class BaseModel(BaseModel):
     @classmethod

g4f/requests/__init__.py

@@ -104,7 +104,8 @@ async def get_args_from_nodriver(
             await browser.cookies.set_all(get_cookie_params_from_dict(cookies, url=url, domain=domain))
         page = await browser.get(url)
         user_agent = await page.evaluate("window.navigator.userAgent", return_by_value=True)
-        await page.wait_for("body:not(.no-js)", timeout=timeout)
+        while not await page.evaluate("document.querySelector('body:not(.no-js)')"):
+            await asyncio.sleep(1)
         if wait_for is not None:
             await page.wait_for(wait_for, timeout=timeout)
         if callback is not None: