fix: Support cyrillic characters

[martinhrvn]

This fixes #25

Root cause of this issue is that strings.Index returns byte index. So I switched the calculation of the indexes to use rune index as well as taking the string up to specified index and from specified index. Mabye the censored string could be changed to []rune and instead of calling takeRunesFromIndex we could just update the censored inplace.

[codecov-commenter]

Codecov Report

Merging #27 (cffad5e) into master (bd63346) will decrease coverage by 0.59%.
The diff coverage is 95.23%.

@@             Coverage Diff             @@
##            master      #27      +/-   ##
===========================================
- Coverage   100.00%   99.40%   -0.60%     
===========================================
  Files            1        1              
  Lines          158      168      +10     
===========================================
+ Hits           158      167       +9     
- Misses           0        1       +1     

Impacted Files	Coverage Δ
goaway.go	99.40% <95.23%> (-0.60%)	⬇️

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[omatija]

Hello @TwiN I work with @martinhrvn and I have a question. Is there any future release planned? If yes can you share the date? We would like to use this fix in our code so is there any chance to release v1.6.1 ?
Thanks

[TwiN]

@omatija I'll release it in a couple minutes; I've just been very busy these past weeks, but since you need it now, I'll accommodate you :)

[TwiN]

Thank you for your contribution!

Released in v1.6.1

[omatija]

Thank you very very much! :)