Update grid.cc #8629

Job	Run time
classicmode_1d_3dgrid	7m 50s
classicmode_3d	7m 14s
kilonova_1d_1dgrid	4m 30s
kilonova_1d_3dgrid	4m 31s
kilonova_2d_2dgrid	8m 28s
kilonova_2d_2dgrid_barnesthermalisation	5m 10s
kilonova_2d_2dgrid_expansionopac	4m 37s
kilonova_2d_2dgrid_xcomgammaphotoion	4m 53s
kilonova_2d_3dgrid	6m 34s
nebular_1d_3dgrid	12m 58s
nebular_1d_3dgrid_limitbfest	13m 16s
combine_checksums	17s
	1h 20m 18s

Provide feedback