I'm having problems with koi8-r encoded messages

[b1rdex]

Such messages body is presented as ??? chars, instead of real chars.
But subject is decoded as it should and have no problem.
Here is message original: https://gist.github.com/b1rdex/387473a0d4f54e0c060388a7d876a31a

[b1rdex]

If I manually mb_convert_encoding($messageBody, 'utf-8', 'koi8-r') it converts good.
mb_convert_encoding($messageBody, 'utf-8') fails autodetection and results ???.

[b1rdex]

Problem is here:

Fetch/src/Fetch/Message.php

Line 526 in 9a1b0eb

if (!in_array($parameters['charset'], mb_list_encodings())) {

Input from email is koi8-r, but mb_list_encodings() has KOI8-R.

[b1rdex]

I created #207 with fix for this.