Remove unused attr_writer

ima1zumi · ima1zumi · commit ecdc1b7116ec · 2020-12-22T13:59:14.000+09:00
diff --git a/lib/reline.rb b/lib/reline.rb
@@ -36,7 +36,6 @@ class Core
     attr_accessor :config
     attr_accessor :key_stroke
     attr_accessor :line_editor
-    attr_writer :ambiguous_width
     attr_accessor :last_incremental_search
     attr_reader :output
 
