cherry-pick(#1430): fix(tasks): cancel all the pending tasks as we exit own loop (#1431)

fix(tasks): cancel all the pending tasks as we exit own loop (#1430)

Author: rwoll

Diff for: playwright/sync_api/_context_manager.py

@@ -98,5 +98,8 @@ def __exit__(self, *args: Any) -> None:
         if self._watcher:
             self._watcher.close()
         if self._own_loop:
+            tasks = asyncio.all_tasks(self._loop)
+            for t in [t for t in tasks if not (t.done() or t.cancelled())]:
+                t.cancel()
             self._loop.run_until_complete(self._loop.shutdown_asyncgens())
             self._loop.close()