README.md: remove no longer relevant badges [ci skip]

Author: rouault

README.md

@@ -1,7 +1,5 @@
 # PROJ
 
-[![Travis Status](https://app.travis-ci.com/OSGeo/PROJ.svg?branch=master)](https://app.travis-ci.com/github/OSGeo/PROJ)
-[![Docker build Status](https://img.shields.io/docker/cloud/build/osgeo/proj)](https://hub.docker.com/r/osgeo/proj/builds)
 [![Coveralls Status](https://coveralls.io/repos/github/OSGeo/PROJ/badge.svg?branch=master)](https://coveralls.io/github/OSGeo/PROJ?branch=master)
 [![Gitter](https://badges.gitter.im/OSGeo/proj.4.svg)](https://gitter.im/OSGeo/proj.4)
 [![Mailing List](https://img.shields.io/badge/PROJ-mailing%20list-4eb899.svg)](http://lists.osgeo.org/mailman/listinfo/proj)