Update alternative links

- pykakasi moved off Github
- kuroshiro has no updates since 2021 (author also not active on github
  since)
- kana (go) had no updates since six years ago

Author: polm

README.md

@@ -91,7 +91,5 @@ nkatu.romaji(sent)
 ## Alternatives
 
 - [kakasi](http://kakasi.namazu.org/index.html.ja): Historically important, but not updated since 2014. 
-- [pykakasi](https://github.com/miurahr/pykakasi): self contained, it does segmentation on its own and uses its own dictionary.
-- [kuroshiro](https://github.com/hexenq/kuroshiro): Javascript based.
-- [kana](https://github.com/gojp/kana): Go based.
+- [pykakasi](https://codeberg.org/miurahr/pykakasi): self contained, it does segmentation on its own and uses its own dictionary.