fix(README): Update coverage (#536)

fix: Update coverage

Signed-off-by: Ce Gao <cegao@tensorchord.ai>

README.md

@@ -4,11 +4,12 @@
 </div>
 
 <p align=center>
-<a href="https://github.com/tensorchord/envd/actions/workflows/CI.yml"><img alt="continuous integration" src="https://github.com/tensorchord/envd/actions/workflows/CI.yml/badge.svg"></a>
-<a href="https://pypi.org/project/envd/"><img alt="envd package donwloads" src="https://static.pepy.tech/personalized-badge/envd?period=month&units=international_system&left_color=grey&right_color=brightgreen&left_text=downloads/month"</a>
 <a href="https://discord.gg/KqswhpVgdU"><img alt="discord invitation link" src="https://img.shields.io/discord/974584200327991326?label=discord&style=social"></a>
 <a href="https://twitter.com/TensorChord"><img src="https://img.shields.io/twitter/follow/tensorchord?style=social" alt="trackgit-views" /></a>
 <a href="https://github.com/tensorchord/envd#contributors-"><img alt="all-contributors" src="https://img.shields.io/github/all-contributors/tensorchord/envd/main"></a>
+<a href="https://pypi.org/project/envd/"><img alt="envd package donwloads" src="https://static.pepy.tech/personalized-badge/envd?period=month&units=international_system&left_color=grey&right_color=brightgreen&left_text=downloads/month"</a>
+<a href="https://github.com/tensorchord/envd/actions/workflows/CI.yml"><img alt="continuous integration" src="https://github.com/tensorchord/envd/actions/workflows/CI.yml/badge.svg"></a>
+<a href='https://coveralls.io/github/tensorchord/envd?branch=main'><img src='https://coveralls.io/repos/github/tensorchord/envd/badge.svg?branch=main' alt='Coverage Status' /></a>
 </p>
 
 > **⚠️ envd is still under heavy development, and subject to change. it is not feature-complete or production-ready. Please contact us in [discord](https://discord.gg/KqswhpVgdU) if there is any problem.**