Don't use IO::Buffer.size_of for old Ruby

IO::Buffer.size_of is available since Ruby 3.4.

Author: kou

lib/flatbuffers/serializer.rb

@@ -17,7 +17,7 @@ class Serializer
     module Alignable
       private
       def align32!(data)
-        padding_size = data.bytesize % IO::Buffer.size_of(:s32)
+        padding_size = data.bytesize % 4 # IO::Buffer.size_of(:s32)
         return if padding_size.zero?
         data.append_as_bytes("\x00" * padding_size)
       end

lib/flatbuffers/view.rb

@@ -14,8 +14,8 @@
 
 module FlatBuffers
   class View
-    OFFSET_SIZE = IO::Buffer.size_of(:u32)
-    VIRTUAL_OFFSET_SIZE = IO::Buffer.size_of(:u16)
+    OFFSET_SIZE = 4 # IO::Buffer.size_of(:u32)
+    VIRTUAL_OFFSET_SIZE = 2 # IO::Buffer.size_of(:u16)
     IDENTIFIER_SIZE = 4
 
     module VTable