[README.md] Fix star badge

README.md

@@ -6,7 +6,7 @@
 
 Uptime Kuma is an easy-to-use self-hosted monitoring tool.
 
-<a target="_blank" href="https://github.com/louislam/uptime-kuma"><img src="https://img.shields.io/github/stars/louislam/uptime-kuma" /></a> <a target="_blank" href="https://hub.docker.com/r/louislam/uptime-kuma"><img src="https://img.shields.io/docker/pulls/louislam/uptime-kuma" /></a> <a target="_blank" href="https://hub.docker.com/r/louislam/uptime-kuma"><img src="https://img.shields.io/docker/v/louislam/uptime-kuma/latest?label=docker%20image%20ver." /></a> <a target="_blank" href="https://github.com/louislam/uptime-kuma"><img src="https://img.shields.io/github/last-commit/louislam/uptime-kuma" /></a>  <a target="_blank" href="https://opencollective.com/uptime-kuma"><img src="https://opencollective.com/uptime-kuma/total/badge.svg?label=Open%20Collective%20Backers&color=brightgreen" /></a>
+<a target="_blank" href="https://github.com/louislam/uptime-kuma"><img src="https://img.shields.io/github/stars/louislam/uptime-kuma?style=flat" /></a> <a target="_blank" href="https://hub.docker.com/r/louislam/uptime-kuma"><img src="https://img.shields.io/docker/pulls/louislam/uptime-kuma" /></a> <a target="_blank" href="https://hub.docker.com/r/louislam/uptime-kuma"><img src="https://img.shields.io/docker/v/louislam/uptime-kuma/latest?label=docker%20image%20ver." /></a> <a target="_blank" href="https://github.com/louislam/uptime-kuma"><img src="https://img.shields.io/github/last-commit/louislam/uptime-kuma" /></a>  <a target="_blank" href="https://opencollective.com/uptime-kuma"><img src="https://opencollective.com/uptime-kuma/total/badge.svg?label=Open%20Collective%20Backers&color=brightgreen" /></a>
 [![GitHub Sponsors](https://img.shields.io/github/sponsors/louislam?label=GitHub%20Sponsors)](https://github.com/sponsors/louislam) <a href="https://weblate.kuma.pet/projects/uptime-kuma/uptime-kuma/">
 <img src="https://weblate.kuma.pet/widgets/uptime-kuma/-/svg-badge.svg" alt="Translation status" />
 </a>