message: Remove unnecessary friend declaration
diff: @@ -44,9 +44,6 @@ constexpr invalid_group_t invalid_group = invalid_group_t{};
  class group : detail::comparable<group>,
  detail::comparable<group, invalid_group_t> {
  public:
  - template <class, class, int>
  - friend class actor_cast_access;
  -
  using signatures = none_t;
  group() = default;
  