fix `#357`

When using 8-bit characters, it is better not to use `compress_meta_key`.
I believe not to use `compress_meta_key` unless `set convert-meta on` is written in the `.inputrc`.

The following is a quote from tmtm's comments.

> The behavior of this compress_meta_key method is similar to the behavior of convert-meta=on in readline, but readline turns off convert-meta if the locale contains 8bit characters.

> In readline(3):

> convert-meta (On)
> If set to On, readline will convert characters with the eighth
> bit set to an ASCII key sequence by stripping the eighth bit and
> prefixing it with an escape character (in effect, using escape
> as the meta prefix). The default is On, but readline will set
> it to Off if the locale contains eight-bit characters.

https://github.com/ruby/reline/commit/9491cc8542



Co-authored-by: TOMITA Masahiro <tommy@tmtm.org>