Type bug in shortest path with threshlod

[BatyLeo]

• ConstrainedShortestPaths.jl/src/algorithms.jl

  Line 167 in 712c73b

  instance::CSPInstance{G}, threshold::Float64

• ConstrainedShortestPaths.jl/src/algorithms.jl

  Line 110 in 712c73b

  instance::CSPInstance{G}, bounds::AbstractVector, threshold::Float64

We should have CSPInstance{T,G} instead of CSPInstance{G}