[packman] Update to the site's contact information

[Marc Schiffbauer]

* Patrick Finie schrieb am 11.12.21 um 14:48 Uhr:
> Earlier this year freenode imploded and the official packman irc channel
> moved to liber.chat.  Sadly the information on the website still points to
> freenode which is very problematic.

Thanks!

fixed...

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