meta: cleanup

TODO

@@ -25,6 +25,5 @@ Next:
  - custom pools.
  - the Perfect Model.
  - page size 0 -> page less mode
- - test meta_associative_container::meta_iterator::value fro non-key-only, const value
  - add ::reach and rev iterators to views and groups for raw, faster and unsafe iterations
  - add example: 64 bit ids with 32 bits reserved for users' purposes

src/entt/meta/meta.hpp

@@ -1695,11 +1695,7 @@ class meta_associative_container::meta_iterator {
         if constexpr(KeyOnly) {
             return meta_any{};
         } else {
-            if constexpr(std::is_const_v<std::remove_reference_t<decltype(std::declval<It>()->second)>>) {
-                return any.cast<It>()->second;
-            } else {
-                return std::ref(any.cast<It>()->second);
-            }
+            return std::ref(any.cast<It>()->second);
         }
     }