test(tutorial3): remove redundant material definitions

Author: amaurigmartins

test/test_tutorial3.jl

@@ -4,12 +4,6 @@
 	mktempdir(joinpath(@__DIR__)) do tmpdir
 		# Materials
 		materials = MaterialsLibrary(add_defaults = true)
-		lead = Material(21.4e-8, 1.0, 0.999983, 20.0, 0.00400)
-		add!(materials, "lead", lead)
-		steel = Material(13.8e-8, 1.0, 300.0, 20.0, 0.00450)
-		add!(materials, "steel", steel)
-		pp = Material(1e15, 2.8, 1.0, 20.0, 0.0)
-		add!(materials, "pp", pp)
 
 		@test haskey(materials, "lead")
 		@test haskey(materials, "steel")