fix: Skip loop close test when async transport deps missing

test_loop_close_flushes_async_transport needs ASYNC_TRANSPORT_ENABLED
to be True. In gevent env (no httpcore[asyncio]), the _flush function
correctly skips async transport handling, so close_async is never
called. Skip the test in that case.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: BYK

tests/integrations/asyncio/test_asyncio.py

@@ -645,7 +645,10 @@ def test_loop_close_patching(sentry_init):
 
 @minimum_python_38
 def test_loop_close_flushes_async_transport(sentry_init):
-    from sentry_sdk.transport import AsyncHttpTransport
+    from sentry_sdk.transport import ASYNC_TRANSPORT_ENABLED, AsyncHttpTransport
+
+    if not ASYNC_TRANSPORT_ENABLED:
+        pytest.skip("httpcore[asyncio] not installed")
 
     sentry_init(integrations=[AsyncioIntegration()])