Add net_elec_cumulative testcase for p1_v2

Author: bouwew

tests/test_smile.py

@@ -759,6 +759,7 @@ async def test_connect_smile_p1_v2(self):
                         "id": "electricity_produced_off_peak_cumulative",
                         "state": 482.598,
                     },
+                    {"id": "net_electricity_cumulative", "state": 1019.151},
                 ]
             }
         }