message: fix range constructor compilation failures
diff: @@ -80,7 +80,7 @@ struct span {
  *
  * @param point the point which the span represents
  */
  - GKO_ATTRIBUTES explicit constexpr span(size_type point) noexcept
  + GKO_ATTRIBUTES constexpr span(size_type point) noexcept
  : span{point, point + 1}
  {}
  