`tapioca gem`: `attr_*` with several names + RBS-comment: not all result methods have sigs

The following code
```ruby
class Foo
  #: Integer
  attr_reader :bar, :baz, :foo
end
```
is compiled to
```ruby
class Foo
  sig { returns(::Integer) }
  def bar; end

  def baz; end
  def foo; end
end
```

In the result, only the first method has a sig, the rest don't. It is expected all the methods to have sigs.