README: Remove LGTM Batches (#1402)

LGTM is now in GitHub CodeQL. We don't get a fancy "grade" and badge
for it anymore.

Author: ax3l

README.md

@@ -9,9 +9,6 @@ C++ & Python API for Scientific I/O with openPMD
 [![License](https://img.shields.io/badge/license-LGPLv3-blue)](https://www.gnu.org/licenses/lgpl-3.0.html)
 [![DOI](https://rodare.hzdr.de/badge/DOI/10.14278/rodare.27.svg)](https://doi.org/10.14278/rodare.27)  
 [![CodeFactor](https://www.codefactor.io/repository/github/openpmd/openpmd-api/badge)](https://www.codefactor.io/repository/github/openpmd/openpmd-api)
-[![LGTM: C/C++](https://img.shields.io/lgtm/grade/cpp/g/openPMD/openPMD-api?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/openPMD/openPMD-api/context:cpp)
-[![LGTM: Python](https://img.shields.io/lgtm/grade/python/g/openPMD/openPMD-api?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/openPMD/openPMD-api/context:python)
-[![LGTM: Total alerts](https://img.shields.io/lgtm/alerts/g/openPMD/openPMD-api?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/openPMD/openPMD-api/alerts/)
 [![Coverage Status](https://coveralls.io/repos/github/openPMD/openPMD-api/badge)](https://coveralls.io/github/openPMD/openPMD-api)  
 [![Documentation Status](https://readthedocs.org/projects/openpmd-api/badge/?version=latest)](https://openpmd-api.readthedocs.io/en/latest/?badge=latest)
 [![Linux/OSX Build Status dev](https://travis-ci.com/openPMD/openPMD-api.svg?branch=dev)](https://travis-ci.com/openPMD/openPMD-api)