Robustify interactive browser

Too small window sizes make the test unstable. Now it works reliably in
a loop.

bidi.py

@@ -116,6 +116,9 @@ class WebdriverBidi:
         else:
             raise WebdriverError("timed out waiting for default realm")
 
+        # avoid not seeing elements due to too small window
+        await self.bidi("browsingContext.setViewport", context=self.context, viewport={"width": 1024, "height": 5000})
+
     async def __aenter__(self):
         await self.start_session()
         return self