CI: update status badges

README.md

@@ -1,8 +1,8 @@
 ## libmypaint - MyPaint brush engine library
 
 [![Translation Status](https://hosted.weblate.org/widgets/mypaint/libmypaint/svg-badge.svg)](https://hosted.weblate.org/engage/mypaint/?utm_source=widget)
-[![Travis Build Status](https://travis-ci.org/mypaint/libmypaint.png?branch=master)](https://travis-ci.org/mypaint/libmypaint)
-[![Appveyor Build Status](https://ci.appveyor.com/api/projects/status/vc6ejt4nba5ctd6r)](https://ci.appveyor.com/project/jonnor/libmypaint)
+[![Travis Build Status](https://travis-ci.org/mypaint/libmypaint.svg?branch=master)](https://travis-ci.org/mypaint/libmypaint)
+[![Appveyor Build Status](https://ci.appveyor.com/api/projects/status/github/mypaint/libmypaint?branch=master&svg=true)](https://ci.appveyor.com/project/jonnor/libmypaint)
 
 This is a self-contained C library that is isolated from MyPaint.
 It allows other applications to make use of the MyPaint brush engine.