message: transform_view: don't use deprecated range_size_type_t
diff: @@ -166,13 +166,13 @@ namespace ranges
  constexpr /*c++14*/ auto CPP_fun(size)() (
  requires SizedRange<Rng>)
  {
  - return static_cast<range_size_type_t<Rng>>(ranges::size(this->base()));
  + return ranges::size(this->base());
  }
  CPP_member
  constexpr auto CPP_fun(size)() (const
  requires SizedRange<Rng const>)
  {
  - return static_cast<range_size_type_t<Rng>>(ranges::size(this->base()));
  + return ranges::size(this->base());
  }
  };
  