Update alphadecays.txt #8282

Job	Run time
classicmode_1d_3dgrid	4m 32s
classicmode_3d	7m 44s
kilonova_1d_1dgrid	4m 43s
kilonova_1d_3dgrid	4m 53s
kilonova_2d_2dgrid	6m 58s
kilonova_2d_2dgrid_barnesthermalisation	5m 52s
kilonova_2d_2dgrid_expansionopac	6m 30s
kilonova_2d_2dgrid_xcomgammaphotoion	5m 13s
kilonova_2d_3dgrid	6m 53s
nebular_1d_3dgrid	11m 27s
nebular_1d_3dgrid_limitbfest	14m 29s
combine_checksums	18s
	1h 19m 32s

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