message: Simplify constraint on subrange constructor
  Fixes
diff: @@ -275,7 +275,7 @@ namespace ranges
  template<typename R>
  constexpr CPP_ctor(subrange)(R && r, size_type n)(
  requires detail::RangeConvertibleTo_<R, I, S> &&
  - True<K == subrange_kind::sized>)
  + (K == subrange_kind::sized))
  : subrange{ranges::begin(r), ranges::end(r), n}
  {
  if(RANGES_CONSTEXPR_IF((bool)SizedRange<R>))
  