[BUGFIX] Wrong IRC URL for Packagist

Packagist complains about current IRC URL format.

Change-Id: Id8abcad6525c06d6941144cd2e1e8ea372cc975a
Releases: 6.2
Resolves: #56713
Reviewed-on: https://review.typo3.org/28211
Reviewed-by: Thomas Maroschik
Tested-by: Thomas Maroschik