Fix display of types in TimeStepTable

[VEZY]

At the moment, we can get an Int printed as a Float64:

TimeStepTable([(a= 1, b = 2.0),])

The issue comes from the fact that values from the TimeStepTable are all promoted to the same type when printing, because we tranform the row into a matrix:

PlantMeteo.jl/src/structs/TimeStepTable.jl

Line 293 in f2c6a7a

t_mat = Tables.matrix(t)

We should prefer iterating over rows of named tuples instead, si we could keep the types of our values.