Fix SQLiteInsert to use casted plan instead of raw plan

[ak2k]

There appears to be an issue where SQLiteInsert uses the raw plan instead of the type-casted plan. The code calls AddCastToSQLiteTypes to create inner_plan but then uses the original plan:

  auto &inner_plan = AddCastToSQLiteTypes(context, planner, *plan);
  auto &insert = planner.Make<SQLiteInsert>(op, op.table, op.column_index_map);
  insert.children.push_back(*plan);  // Should this be inner_plan?

[Mytherin]

Thanks!