fix CI on 1.5 (#585)

Author: mzgubic

test/projection.jl

@@ -149,9 +149,11 @@ struct NoSuperType end
 
     @testset "Base: Tuple" begin
         pt1 = ProjectTo((1.0,))
-        @test @inferred(pt1((1 + im,))) == Tangent{Tuple{Float64}}(1.0,)
-        @test @inferred(pt1(pt1((1,)))) == pt1(pt1((1,)))            # accepts correct Tangent
-        @test @inferred(pt1(Tangent{Any}(1))) == pt1((1,))           # accepts Tangent{Any}
+        if VERSION >= v"1.6"
+            @test @inferred(pt1((1 + im,))) == Tangent{Tuple{Float64}}(1.0)
+            @test @inferred(pt1(pt1((1,)))) == pt1(pt1((1,)))            # accepts correct Tangent
+            @test @inferred(pt1(Tangent{Any}(1))) == pt1((1,))           # accepts Tangent{Any}
+        end
         @test pt1([1,]) == Tangent{Tuple{Float64}}(1.0,)  # accepts Vector
         @test @inferred(pt1(NoTangent())) === NoTangent()
         @test @inferred(pt1(ZeroTangent())) === ZeroTangent()