vmupdate/dnf: use --setopt=obsoletes=1 instead of --obsoletes

DNF5 dropped that CLI option, but the config option remained:
https://github.com/rpm-software-management/dnf5/blob/main/doc/changes_from_dnf4.7.rst

QubesOS/qubes-issues#9244

(cherry picked from commit a5eb27d)

vmupdate/agent/source/dnf/dnf_cli.py

@@ -95,7 +95,7 @@ def get_action(self, remove_obsolete) -> List[str]:
         Disable or enforce obsolete flag in dnf/yum.
         """
         if remove_obsolete:
-            return ["-y", "--obsoletes", "upgrade"]
+            return ["-y", "--setopt=obsoletes=1", "upgrade"]
         return ["-y", "--setopt=obsoletes=0",
                 "upgrade" if self.package_manager == "dnf" else "update"]