README.md: fix CI badge

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

Author: AkihiroSuda

README.md

@@ -1,6 +1,6 @@
 # [containerd](https://github.com/containerd/containerd) ZFS snapshotter plugin
 
-[![Build Status](https://travis-ci.org/containerd/zfs.svg)](https://travis-ci.org/containerd/zfs)
+[![Build Status](https://github.com/containerd/zfs/workflows/CI/badge.svg)](https://github.com/containerd/zfs/actions?query=workflow%3ACI)
 [![codecov](https://codecov.io/gh/containerd/zfs/branch/master/graph/badge.svg)](https://codecov.io/gh/containerd/zfs)
 
 ZFS snapshotter plugin for containerd.