Update README.md

Author: andyzhangx

README.md

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 # Blobfuse CSI driver for Kubernetes
-[![Coverage Status](https://coveralls.io/github/kubernetes-sigs/blobfuse-csi-driver?branch=master)](https://coveralls.io/github/kubernetes-sigs/blobfuse-csi-driver?branch=master)
+[![Coverage Status](https://coveralls.io/repos/github/kubernetes-sigs/blobfuse-csi-driver/badge.svg?branch=master)](https://coveralls.io/github/kubernetes-sigs/blobfuse-csi-driver?branch=master)
 [![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fkubernetes-sigs%2Fblobfuse-csi-driver.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fkubernetes-sigs%2Fblobfuse-csi-driver?ref=badge_shield)
 
 ### About