Fix test as per Lyndon's suggestion

Co-Authored-By: Lyndon White <oxinabox@ucc.asn.au>

Author: willtebbutt

test/differentials.jl

@@ -5,6 +5,7 @@
         @test wirtinger_conjugate(w) == 2+2im
         @test w + w == Wirtinger(2+2im, 4+4im)
 
+        @testset w + 1 == w + Thunk(()->1) == Wirtinger(2+1im, 2+2im)
         @test w * 2 == 2 * w == Wirtinger(2 + 2im, 4 + 4im)
 
         # TODO: other + methods stack overflow