Update grid.cc #8633

Job	Run time
classicmode_1d_3dgrid	7m 52s
classicmode_3d	7m 30s
kilonova_1d_1dgrid	4m 32s
kilonova_1d_3dgrid	4m 29s
kilonova_2d_2dgrid	6m 36s
kilonova_2d_2dgrid_barnesthermalisation	5m 0s
kilonova_2d_2dgrid_expansionopac	4m 34s
kilonova_2d_2dgrid_xcomgammaphotoion	4m 53s
kilonova_2d_3dgrid	6m 24s
nebular_1d_3dgrid	10m 56s
nebular_1d_3dgrid_limitbfest	13m 22s
combine_checksums	21s
	1h 16m 29s

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