Unnecessary double call to `counts` for `association(::JointProbabilities{<:MIShannon}, x, y)`

[kahaaga]

In the file methods/information/definitions/mutual_informations/MIShannon.jl:

The cts = counts(est.discretization, x, y) line is completely unnecessary. The counts are automatically computed when calling probabilities on the line below. This extra line essentially doubles computation time.