ci: add aiohttp-cors to test requirements

The integration declares `http` as a manifest dependency; HA's http
component imports aiohttp_cors during config-flow tests. It was present
in the local venv (installed manually) but not pinned, so fresh CI failed
with "No module named 'aiohttp_cors'". Pin it so CI reproduces the green
local baseline.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Antonio ...

requirements_test.txt

@@ -5,3 +5,7 @@ pytest
 pytest-homeassistant-custom-component==0.12.49
 pytest-asyncio
 pytest-cov
+# Required to set up the `http` dependency declared in manifest.json during
+# config-flow tests (HA's http component imports aiohttp_cors). Absent from the
+# base test package, so CI fails with "No module named 'aiohttp_cors'" without it.
+aiohttp-cors