GHA: disable mkosi/opensuse

Tumbleweed is too far ahead of v256-stable as it uses 257 already, and
downgrading is not possible, so disable it

Author: bluca

.github/workflows/mkosi.yml

@@ -89,13 +89,6 @@ jobs:
             cflags: "-Og"
             relabel: yes
             qemu: 0
-          - distro: opensuse
-            release: tumbleweed
-            sanitizers: ""
-            llvm: 0
-            cflags: "-Og"
-            relabel: no
-            qemu: 0
           - distro: centos
             release: "9"
             sanitizers: ""