update version to v1.13.1

Author: oilbeater

Diff for: mkdocs.yml

@@ -263,7 +263,7 @@ extra:
     - icon: fontawesome/brands/docker
       link: https://hub.docker.com/r/kubeovn/kube-ovn
   variables:
-    version: v1.13.0
+    version: v1.13.1
     branch: release-1.13
 copyright:
   <p>The Linux Foundation has registered trademarks and uses trademarks. For a list of trademarks of The Linux Foundation,