Code of conduct: update the used IRC network

https://archlinux.org/news/move-of-official-irc-channels-to-liberachat/

code-of-conduct.md

@@ -377,9 +377,9 @@ Guidelines for the [Arch User Repository](https://aur.archlinux.org/) can be fou
 
 ### IRC
 
-All [Arch IRC channels](https://wiki.archlinux.org/index.php/Arch_IRC_channels) are on the freenode
-IRC network. Users on freenode must follow the [network policy](https://freenode.net/policies) and
-freenode [channel guidelines](https://freenode.net/changuide).
+All [Arch IRC channels](https://wiki.archlinux.org/index.php/Arch_IRC_channels) are on the Libera
+Chat IRC network. Users on Libera Chat must follow the [network policy](
+https://libera.chat/policies) and Libera Chat [channel guidelines](https://libera.chat/guidelines).
 
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 language, search [international arch channels](