Set load_shedding genartors control to PQ

This happens within the pf_post_lopf anyhow. But before, the change was only done for the aggregated and not the disaggregated network which resulted into problems when disaggregating

etrago/tools/utilities.py

@@ -635,6 +635,7 @@ def load_shedding(self, temporal_disaggregation=False, **kwargs):
                     p_nom=p_nom,
                     carrier="load shedding",
                     bus=network.buses.index,
+                    control="PQ",
                 ),
                 index=index,
             ),