fix era5 config (ecmwf#473)

Adding z back in

Author: clessig

config/streams/streams_anemoi/era5.yml

@@ -13,7 +13,7 @@ ERA5 :
   # source : ['u_', 'v_', '10u', '10v']
   # target : ['10u', '10v']
   source_exclude : ['w_', 'skt', 'tcw', 'cp', 'tp']
-  target_exclude : ['w_', 'slor', 'sdor', 'z', 'tcw', 'cp', 'tp']
+  target_exclude : ['w_', 'slor', 'sdor', 'tcw', 'cp', 'tp']
   loss_weight : 1.
   masking_rate : 0.6
   masking_rate_none : 0.05