Possible fix for some dew and bubble computations

[Sush1090]

Hello,
As of now the following will fail:

using Clapeyron
fluids =["butane","toluene"]
global model = cPR(fluids,idealmodel = ReidIdeal)
p = 202650.0; z = [ 0.03660834309918798 ,0.5195534741939288]*100

dew_temperature(model,p,z)

This is because the interval provided to volume_from_spinodal cannot find roots.
The possible fix I have for now is not providing this interval (maybe this will mess some other cases):

function volume_from_spinodal(p,poly,vshift,v0)
    if length(v0) == 2
        v0 = v0[2]
    end
    f(v) = p - evalpoly(v,poly)
    prob = Roots.ZeroProblem(f,v0)
    return Roots.solve(prob) + vshift
end

julia> dew_temperature(model,p,z)
(406.4174457072442, 0.00012067728202751558, 0.015760540593102064, [0.0053723341003248356, 0.9946276658996752])

The root finder seems to work without providing the lower bound of 0.

[longemen3000]

A smaller reproducer:

model = cPR("butane")
Clapeyron.x0_sat_pure(model,406.5487245045052)

the problem on the generation of the bracket itself, in this particular case, the bracket does not contain the objective spinodal mean pressure ((p_spinodal_l + p_spinodal_v)/2)

[longemen3000]

08539a5 fixes the issue, but as always, this issue will be closed at the next release