Replace deprecated unsorted_arguments with arguments

Author: bowenszhu

src/systems/connectors.jl

@@ -85,7 +85,7 @@ function collect_instream!(set, expr, occurs = false)
     iscall(expr) || return occurs
     op = operation(expr)
     op === instream && (push!(set, expr); occurs = true)
-    for a in SymbolicUtils.unsorted_arguments(expr)
+    for a in SymbolicUtils.arguments(expr)
         occurs |= collect_instream!(set, a, occurs)
     end
     return occurs

src/utils.jl

@@ -281,7 +281,7 @@ function _check_operator_variables(eq, op::T, expr = eq.rhs) where {T}
         throw_invalid_operator(expr, eq, op)
     end
     foreach(expr -> _check_operator_variables(eq, op, expr),
-        SymbolicUtils.unsorted_arguments(expr))
+        SymbolicUtils.arguments(expr))
 end
 """
 Check if all the LHS are unique