incorrect hash key when select alias by using symbol as arguments

If use string, it's correct
```rb
User.pluck_h('id AS d')  # => [{"d"=>2}, {"d"=>1}] 
```
But if use symbol, the output is wrong
```rb
User.pluck_h(:'id AS d') # => [{"id AS d"=>2}, {"id AS d"=>1}] 
```