[Serializer] XmlEncoder doesn't ignore PI nodes while encoding

[javiereguiluz]

symfony/symfony#27926

[carsonbot]

Thank you for this issue.
There has not been a lot of activity here for a while. Has this been resolved?

[carsonbot]

Friendly ping? Should this still be open? I will close if I don't hear anything.

[wouterj]

Fixed by #14384