Bump system/systemd-boot to 259

Signed-off-by: ci-robbot <robot@c3os.io>

Author: ci-robbot

packages/system/systemd/collection.yaml

@@ -1,7 +1,7 @@
 packages:
   - name: "systemd-boot"
     category: "system"
-    version: "256.17"
+    version: "259"
     labels:
       github.repo: "systemd"
       autobump.revdeps: "true"