Ignore warnings to prevent failing build

[bartaz]

Done

Version 10.3 of linkchecker throws warnings on redirects and fails the build (https://linkchecker.github.io/linkchecker/upgrading.html#migrating-from-10-2-to-10-3).

This PR ignores linkchecker redirect warnings to prevent them from failing the CI.

QA

• make sure linkchecker CI job passes

[webteam-app]

Demo starting at https://design-ubuntu-com-304.demos.haus

[bartaz]

Thanks @minkyngkm, I forgot about this one 😅