Update systems.jl

Author: ChrisRackauckas

test/systems.jl

@@ -100,7 +100,7 @@ trueeqs = Equation[default_time_deriv()(s1) ~ -((k1 * s1 * s2) / c1),
 @test isequal(Catalyst.get_eqs(odesys), trueeqs)
 @test isequal(Catalyst.get_iv(odesys), IV)
 @test isequal(Catalyst.get_unknowns(odesys), [s1, s1s2, s2])
-@test issetequal(Catalyst.parameters_toplevel(odesys), [k1, c1])
+@test issetequal(ModelingToolkit.parameters_toplevel(odesys), [k1, c1])
 u0 = [s1 => 2 * 1.0, s2 => 2 * 1.0, s1s2 => 2 * 1.0]
 par = [k1 => 1.0, c1 => 2.0]
 testdef = merge(Dict(u0), Dict(par))