Update wuschel.jl

Author: ChrisRackauckas

test/wuschel.jl

@@ -13,7 +13,7 @@ m = readSBMLFromString(sbml, doc -> begin
 end)
 sys = ODESystem(m)
 @test length(equations(sys)) == 1012
-@test length(states(sys)) == 1012
+@test length(unknowns(sys)) == 1012
 #ssys = structural_simplify(sys)  # Todo: Figure out why this complains about ExtraVariablesSystemException
 prob = ODEProblem(sys, [], (0, 10.0))
 solve(prob, Tsit5(), save_everystep = false)