Update feed-io to 6.0

[Grotax]

Summary

Since News requires PHP 8.2+ now we could upgrade feed-io to 6.0 hopefully fixing some deprecations.

• the setup of feed-io changed with feed-io 6.0
• there is still a bug in feed-io breaking links PRs are open

[IgorA100]

@Grotax
If you checked my PR alexdebril/feed-io#433 that would be great!
It should work without problems.

I found a problem in feed-io 6.0, but it was never fixed: alexdebril/feed-io#421
Or maybe it's not a problem. Everyone is silent...

[Grotax]

What would me checking it do though? I don't have merge rights.

[IgorA100]

What would I check it though?

To be sure that everything works 100% correctly.

I don't have merge rights.

I know. But if you suddenly find a problem - I will try to fix it quickly in feed-io

[Grotax]

One step on this road will be to improve code quality, I'm tired of people opening issues because of deprecation warnings in their logs.

feed-io 6 as it turns out is also not there yet so we need to do that.

php-feed-io/feed-io#16

Other open topics are the open PRs for feed-io not sure all will be merged.

If the deprecation warnings are gone and the important prs merged I think news could move to version 6

[Grotax]

Done