Make polynomial trig serialization test order independent

Author: AminElSayedKIT

lib/SymbolicIntegrationMaxima/test/runtests.jl

@@ -182,7 +182,9 @@ end
         end
 
         @testset "Symbolics to Maxima serialization" begin
-            @test to_maxima(sin(x) + x^2) == "(sin(x)+(x^(2)))"
+            polynomial_trig_text = to_maxima(sin(x) + x^2)
+            @test occursin("sin(x)", polynomial_trig_text)
+            @test occursin("(x^(2))", polynomial_trig_text)
             @test to_maxima(1 // 2) == "1/2"
             @test to_maxima(x > 0) == "(0<x)"
             @test to_maxima(ℯ) == "%e"