refactor: fix typo

Author: draincoder

src/asgi_monitor/integrations/aiohttp.py

@@ -199,8 +199,8 @@ async def tracing_middleware(request: Request, handler: Callable) -> Any:
             try:
                 resp = await handler(request)
                 _set_status_code(span, resp.status)
-            except HTTPException as ex:
-                _set_status_code(span, ex.status_code)
+            except HTTPException as exc:
+                _set_status_code(span, exc.status_code)
                 raise
             finally:
                 duration = max((default_timer() - start) * 1000, 0)