Remove Pharo 7.0 badge

Author: SergeStinckwich

README.md

@@ -12,7 +12,6 @@
   </p>
 </p>
 
-[![Pharo version](https://img.shields.io/badge/Pharo-7.0-%23aac9ff.svg)](https://pharo.org/download)
 [![Pharo version](https://img.shields.io/badge/Pharo-8.0-%23aac9ff.svg)](https://pharo.org/download)
 [![Build Status](https://travis-ci.org/PolyMathOrg/PolyMath.svg?branch=master)](https://travis-ci.org/PolyMathOrg/PolyMath)
 [![Build status](https://ci.appveyor.com/api/projects/status/3tvarh2xi22max8h?svg=true)](https://ci.appveyor.com/project/SergeStinckwich/polymath-88bea)