Fix CSE tests due to new DAG implementation

Author: bowenszhu

test/cse.jl

@@ -6,9 +6,9 @@ using SymbolicUtils.Code: topological_sort
     t = cse(hypot(hypot(cos(x), sin(x)), atan(cos(x), sin(x))))
 
     @test t isa Let
-    @test length(t.pairs) == 2
-    @test occursin(t.pairs[1].lhs, t.body)
-    @test occursin(t.pairs[2].lhs, t.body)
+    @test length(t.pairs) == 4
+    @test occursin(t.pairs[3].lhs, t.body)
+    @test occursin(t.pairs[4].lhs, t.body)
 end
 
 @testset "DAG CSE" begin