Update README.md

Author: andyzhangx

README.md

@@ -1,5 +1,5 @@
 # Azure Blob Storage CSI driver for Kubernetes
-[![Travis](https://travis-ci.org/kubernetes-sigs/blob-csi-driver.svg)](https://travis-ci.org/kubernetes-sigs/blob-csi-driver)
+![linux build status](https://github.com/kubernetes-sigs/blob-csi-driver/actions/workflows/linux.yaml/badge.svg)
 [![Coverage Status](https://coveralls.io/repos/github/kubernetes-sigs/blob-csi-driver/badge.svg?branch=master)](https://coveralls.io/github/kubernetes-sigs/blob-csi-driver?branch=master)
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