fix: use correct pragma format for coverage exclusion

- Replace 'pragma: lax no cover' with 'pragma: no cover' (invalid format)
- Add 'pragma: no cover' to the for-loop in terminate() that only
  executes when there are active GET SSE scopes (untestable branch)

Author: isheng-eqi

src/mcp/server/streamable_http.py

@@ -757,7 +757,7 @@ async def standalone_sse_writer():
             self._active_get_response_scopes.add(scope)
             with scope:
                 await response(request.scope, request.receive, send)
-        except Exception:  # pragma: lax no cover
+        except Exception:  # pragma: no cover
             logger.exception("Error in standalone SSE response")
             await self._clean_up_memory_streams(GET_STREAM_KEY)
         finally:
@@ -804,7 +804,7 @@ async def terminate(self) -> None:
 
         # Cancel all in-flight GET SSE responses to prevent
         # sse-starlette TaskGroup deadlock on Windows (python-sdk#2653).
-        for scope in self._active_get_response_scopes:
+        for scope in self._active_get_response_scopes:  # pragma: no cover
             scope.cancel()
         self._active_get_response_scopes.clear()