Add .NET 9 to CI #609

Job	Run time
Verify tests pass (docker.io/library/alpine:latest, 6.0)	7m 9s
Verify tests pass (docker.io/library/alpine:latest, 8.0)	8m 25s
Verify tests pass (docker.io/library/alpine:edge, 6.0)	7m 21s
Verify tests pass (docker.io/library/alpine:edge, 8.0)	8m 4s
Verify tests pass (quay.io/centos/centos:stream9, 6.0)	7m 43s
Verify tests pass (quay.io/centos/centos:stream9, 8.0)	21s
Verify tests pass (registry.fedoraproject.org/fedora:39, 6.0)	8m 9s
Verify tests pass (registry.fedoraproject.org/fedora:39, 8.0)	8m 52s
Verify tests pass (registry.fedoraproject.org/fedora:40, 6.0)	8m 14s
Verify tests pass (registry.fedoraproject.org/fedora:40, 8.0)	9m 12s
Verify tests pass (registry.fedoraproject.org/fedora:rawhide, 6.0)	8m 17s
Verify tests pass (registry.fedoraproject.org/fedora:rawhide, 8.0)	8m 13s
Verify tests pass (registry.access.redhat.com/ubi8, 6.0)	8m 4s
Verify tests pass (registry.access.redhat.com/ubi8, 8.0)	8m 13s
Verify tests pass (registry.access.redhat.com/ubi9, 6.0)	7m 42s
Verify tests pass (registry.access.redhat.com/ubi9, 8.0)	8m 25s
Verify tests pass (registry.fedoraproject.org/fedora:40, 9.0)	8m 45s
	2h 11m 9s

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