readme: update badges

Author: jcarpent

README.md

@@ -6,6 +6,7 @@
   <a href="https://opensource.org/licenses/BSD-2-Clause"><img src="https://img.shields.io/badge/License-BSD%202--Clause-green.svg" alt="License"/></a>
   <a href="https://github.com/Simple-Robotics/proxsuite/actions/workflows/ci-linux-osx-win-conda.yml"><img src="https://github.com/Simple-Robotics/proxsuite/actions/workflows/ci-linux-osx-win-conda.yml/badge.svg?branch=main" alt="CI - Linux/OSX/Windows - Conda"></a>
   <a href="https://badge.fury.io/py/proxsuite"><img src="https://badge.fury.io/py/proxsuite.svg" alt="PyPI version" height="20"></a>
+  <a href="https://anaconda.org/conda-forge/proxsuite"><img src="https://anaconda.org/conda-forge/proxsuite/badges/version.svg" alt="Conda version" height="20"></a>
 </p>
 
 **ProxSuite** is a collection of open-source, numerically robuste, precise and efficient numerical solvers (e.g., LPs, QPs, etc.) rooted on revisited primal-dual proximal algorithms.