meta: const correctness

src/entt/meta/container.hpp

@@ -147,7 +147,7 @@ class basic_meta_associative_container_traits {
     using size_type = typename meta_associative_container::size_type;
     using iterator = typename meta_associative_container::iterator;
 
-    static size_type basic_vtable(const operation op, const void *cvalue, void *value, meta_any *key, iterator *it) {
+    static size_type basic_vtable(const operation op, const void *cvalue, void *value, const meta_any *key, iterator *it) {
         switch(op) {
         case operation::size:
             return static_cast<const Type *>(cvalue)->size();

src/entt/meta/meta.hpp

@@ -137,7 +137,7 @@ private:
     internal::meta_type_node (*key_type_node)(const internal::meta_context &){};
     internal::meta_type_node (*mapped_type_node)(const internal::meta_context &){};
     internal::meta_type_node (*value_type_node)(const internal::meta_context &){};
-    size_type (*vtable)(const operation, const void *, void *, meta_any *, iterator *){};
+    size_type (*vtable)(const operation, const void *, void *, const meta_any *, iterator *){};
     any storage{};
 };