use same name to type object

Follow up to #24079

activemodel/lib/active_model/type.rb

@@ -47,7 +47,7 @@ def lookup(*args, **kwargs) # :nodoc:
     register(:binary, Type::Binary)
     register(:boolean, Type::Boolean)
     register(:date, Type::Date)
-    register(:date_time, Type::DateTime)
+    register(:datetime, Type::DateTime)
     register(:decimal, Type::Decimal)
     register(:float, Type::Float)
     register(:immutable_string, Type::ImmutableString)

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -815,7 +815,7 @@ def construct_coder(row, coder_class)
         ActiveRecord::Type.register(:bit_varying, OID::BitVarying, adapter: :postgresql)
         ActiveRecord::Type.register(:binary, OID::Bytea, adapter: :postgresql)
         ActiveRecord::Type.register(:cidr, OID::Cidr, adapter: :postgresql)
-        ActiveRecord::Type.register(:date_time, OID::DateTime, adapter: :postgresql)
+        ActiveRecord::Type.register(:datetime, OID::DateTime, adapter: :postgresql)
         ActiveRecord::Type.register(:decimal, OID::Decimal, adapter: :postgresql)
         ActiveRecord::Type.register(:enum, OID::Enum, adapter: :postgresql)
         ActiveRecord::Type.register(:hstore, OID::Hstore, adapter: :postgresql)