fix typo in README

Author: Remi-Gau

README.md

@@ -1,7 +1,7 @@
 [![](https://img.shields.io/badge/Octave-CI-blue?logo=Octave&logoColor=white)](https://github.com/cpp-lln-lab/CPP_PTB/actions)
 ![](https://github.com/cpp-lln-lab/CPP_PTB/workflows/CI/badge.svg) 
 
-[![Build Status](https://travis-ci.com/cpp-lln-lab/CPP_BIDS.svg?branch=master)](https://travis-ci.com/cpp-lln-lab/CPP_PTB)
+[![Build Status](https://travis-ci.com/cpp-lln-lab/CPP_PTB.svg?branch=master)](https://travis-ci.com/cpp-lln-lab/CPP_PTB)
 
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