Add Julia ecosystem to Dependabot configuration #1026

Job	Run time
SciMLBase.jl/Core/1	5m 18s
OrdinaryDiffEq.jl/Core/1	13m 29s
DelayDiffEq.jl/Interface/1	18m 7s
DiffEqSensitivity.jl/Core/1	1m 15s
OrdinaryDiffEq.jl/Interface/1	34s
SciMLSensitivity.jl/Core5/1	2h 41m 5s
SciMLSensitivity.jl/Core1/1	47m 16s
SciMLSensitivity.jl/Core2/1	32m 50s
SciMLSensitivity.jl/Core4/1	5m 44s
DiffEqBase.jl/Downstream/1	1m 26s
SciMLSensitivity.jl/Core6/1	9s
SciMLSensitivity.jl/Core3/1	1m 17s
LabelledArrays.jl/RecursiveArrayTools/1	36s
DiffEqBase.jl/Downstream2/1	18m 40s
DiffEqBase.jl/Core/1	2m 0s
	5h 9m 46s

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