enable hashing of std::vector<bool>

it's iterable but there's no hash function
for the wrapper type
but there's `std::hash<std::vector<bool>>`
so we use it

include/cista/hashing.h

@@ -100,6 +100,8 @@ struct hashing {
  : hash(std::string_view{&(*begin(el)), el.size()}, seed);
  } else if constexpr (std::is_scalar_v<Type>) {
  return hash_combine(seed, el);
+ } else if constexpr (has_std_hash_v<Type>) {
+ return hash_combine(std::hash<Type>()(el), seed);
  } else if constexpr (is_iterable_v<Type>) {
  auto h = seed;
  for (auto const& v : el) {
@@ -114,8 +116,6 @@ struct hashing {
  return h;
  } else if constexpr (is_strong_v<Type>) {
  return hashing<typename Type::value_t>{}(el.v_, seed);
- } else if constexpr (has_std_hash_v<Type>) {
- return hash_combine(std::hash<Type>()(el), seed);
  } else {
  static_assert(has_hash_v<Type> || std::is_scalar_v<Type> ||
  has_std_hash_v<Type> || is_iterable_v<Type> ||