Update grid.cc #8652

Job	Run time
classicmode_1d_3dgrid	7m 49s
classicmode_3d	7m 21s
kilonova_1d_1dgrid	5m 18s
kilonova_1d_3dgrid	6m 2s
kilonova_2d_2dgrid	6m 14s
kilonova_2d_2dgrid_barnesthermalisation	5m 12s
kilonova_2d_2dgrid_expansionopac	4m 36s
kilonova_2d_2dgrid_xcomgammaphotoion	4m 54s
kilonova_2d_3dgrid	6m 38s
nebular_1d_3dgrid	11m 3s
nebular_1d_3dgrid_limitbfest	13m 9s
combine_checksums	16s
	1h 18m 32s

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