Update grid.cc #8631

Job	Run time
classicmode_1d_3dgrid	7m 49s
classicmode_3d	7m 13s
kilonova_1d_1dgrid	4m 21s
kilonova_1d_3dgrid	4m 41s
kilonova_2d_2dgrid	6m 19s
kilonova_2d_2dgrid_barnesthermalisation	5m 15s
kilonova_2d_2dgrid_expansionopac	4m 27s
kilonova_2d_2dgrid_xcomgammaphotoion	4m 56s
kilonova_2d_3dgrid	6m 35s
nebular_1d_3dgrid	11m 9s
nebular_1d_3dgrid_limitbfest	13m 17s
combine_checksums	24s
	1h 16m 26s

Provide feedback