add remake test for SCCNonlinearProblem

Author: SebastianM-C

test/downstream/modelingtoolkit_remake.jl

@@ -321,6 +321,7 @@ end
     @test state_values(sccprob2) ≈ 2ones(3)
     @test sccprob2.probs[1].u0 ≈ 2ones(2)
     @test sccprob2.probs[2].u0 ≈ 2ones(1)
+    @test sccprob2.explicitfuns! !== missing
 
     sccprob3 = remake(sccprob; p = [σ => 2.0])
     @test sccprob3.p === sccprob3.probs[1].p