Drop D9 support

Rajan Kumar@2026 → made their first commit to this issue’s fork.

@TR can we enable a phpunit next minor and major in the gitlab or are you planning to create new issue for phpunit failures?

I am currently experimenting with that in the scheduled pipelines, and will make the changes to .gitlab-ci.yml when I have a workable set of tests.

MR testing is turned on for D11 now. All green.

Leaving this issue open because I have to review the dependencies and releases for this branch and for 2.0.x and 8.x-1.x.