templates: update openSUSE Leap to 15.4

Signed-off-by: Akihiro Suda <[email protected]>

Author: AkihiroSuda

examples/opensuse.yaml

@@ -1,7 +1,7 @@
 # This example requires Lima v0.7.0 or later
 images:
 # Hint: run `limactl prune` to invalidate the "Current" cache
-- location: https://download.opensuse.org/distribution/leap/15.3/appliances/openSUSE-Leap-15.3-JeOS.x86_64-15.3-OpenStack-Cloud-Current.qcow2
+- location: https://download.opensuse.org/distribution/leap/15.4/appliances/openSUSE-Leap-15.4-JeOS.x86_64-15.4-OpenStack-Cloud-Current.qcow2
   arch: "x86_64"
 # No aarch64 OpenStack build found :(
 mounts: