Fix distance between EmptySets

[schillic]

The implementation added in #3672 was not correct.
The distance to an empty set is the infimum over the empty set, which is Inf.

LazySets.jl/src/API/Binary/distance.jl

Lines 18 to 23 in efdaaf3

	The standard distance is zero if the sets intersect and otherwise the ``p``-norm
	of the shortest line segment between any pair of points. Formally,
	```math
	\\inf_{x ∈ H_1, y ∈ H_2} \\{ d(x, y) \\}.
	```