Update core_tests.jl

Author: ChrisRackauckas

lib/SCCNonlinearSolve/test/core_tests.jl

@@ -5,7 +5,8 @@ include("../../../common/common_rootfind_testing.jl")
 end
 
 @testitem "Manual SCC" setup=[CoreRootfindTesting] tags=[:core] begin
-    using NonlinearSolve
+    using NonlinearSolveFirstOrder
+    
     function f(du, u, p)
         du[1] = cos(u[2]) - u[1]
         du[2] = sin(u[1] + u[2]) + u[2]