Readme.md: update dependency status image link (png->svg)

README.md

@@ -6,7 +6,7 @@
 [![Greenkeeper badge](https://badges.greenkeeper.io/opensheetmusicdisplay/opensheetmusicdisplay.svg)](https://greenkeeper.io/)
 [![Travis Build Status](https://travis-ci.org/opensheetmusicdisplay/opensheetmusicdisplay.svg?branch=master)](https://travis-ci.org/opensheetmusicdisplay/opensheetmusicdisplay)
 [![Appveyor Build status](https://ci.appveyor.com/api/projects/status/r88lnffso55nq1ko?svg=true)](https://ci.appveyor.com/project/sebastianhaas/opensheetmusicdisplay/branch/master)
-[![Dependency Status](https://david-dm.org/opensheetmusicdisplay/opensheetmusicdisplay.png)](https://david-dm.org/opensheetmusicdisplay/opensheetmusicdisplay)
+[![Dependency Status](https://david-dm.org/opensheetmusicdisplay/opensheetmusicdisplay/status.svg)](https://david-dm.org/opensheetmusicdisplay/opensheetmusicdisplay)
 [![Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/opensheetmusicdisplay/opensheetmusicdisplay?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Commitizen friendly](https://img.shields.io/badge/commitizen-friendly-brightgreen.svg)](http://commitizen.github.io/cz-cli/)