Update grid.cc #8630

Job	Run time
classicmode_1d_3dgrid	7m 56s
classicmode_3d	7m 11s
kilonova_1d_1dgrid	4m 15s
kilonova_1d_3dgrid	4m 27s
kilonova_2d_2dgrid	6m 21s
kilonova_2d_2dgrid_barnesthermalisation	5m 13s
kilonova_2d_2dgrid_expansionopac	4m 26s
kilonova_2d_2dgrid_xcomgammaphotoion	4m 55s
kilonova_2d_3dgrid	6m 48s
nebular_1d_3dgrid	11m 6s
nebular_1d_3dgrid_limitbfest	13m 20s
combine_checksums	21s
	1h 16m 19s

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