style: all other badges are rounded, why not the readme one?

README.md

@@ -5,7 +5,7 @@
 [![Build Status](https://github.com/roedoejet/g2p/actions/workflows/tests.yml/badge.svg)](https://github.com/roedoejet/g2p/actions)
 [![PyPI package](https://img.shields.io/pypi/v/g2p.svg)](https://pypi.org/project/g2p/)
 [![license](https://img.shields.io/badge/Licence-MIT-green)](LICENSE)
-[![standard-readme compliant](https://img.shields.io/badge/readme%20style-standard-brightgreen.svg?style=flat-square)](https://github.com/roedoejet/g2p)
+[![standard-readme compliant](https://img.shields.io/badge/readme%20style-standard-brightgreen.svg)](https://github.com/roedoejet/g2p)
 
 > Grapheme-to-Phoneme transformations that preserve input and output indices!