test: drop redundant local asyncio import

asyncio is already module-level imported (line 16); the inner import in
test_mount_ucp_routes_aiohttp_registers_three_routes shadowed it for no
reason. Caught by github-code-quality bot on PR #49.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: vvillait88

tests/test_seamless_helpers.py

@@ -1702,8 +1702,6 @@ def test_mount_ucp_routes_django_appends_urlpatterns() -> None:
 
 
 def test_mount_ucp_routes_aiohttp_registers_three_routes() -> None:
-    import asyncio
-
     from aiohttp import web
     from aiohttp.test_utils import TestClient, TestServer