wasm tests: Update window class in Selenium test

Rename qt-window to qt-decorated-window to follow changes introduced by:
2ab07b4.

Change-Id: I41f84cc201821d620be11b67939aa94664a8d208
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

tests/auto/wasm/selenium/qwasmwindow.py

@@ -667,7 +667,7 @@ def query_windows(self):
         shadow_container = self.element.find_element(By.CSS_SELECTOR, f'#qt-shadow-container')
         return [
             Window(self, element=element) for element in shadow_container.shadow_root.find_elements(
-                    By.CSS_SELECTOR, f'div#{self.name} > div.qt-window')]
+                    By.CSS_SELECTOR, f'div#{self.name} > div.qt-decorated-window')]
 
     def find_element(self, method, query):
         shadow_container = self.element.find_element(By.CSS_SELECTOR, f'#qt-shadow-container')