Remove Coverity scan badge

Remove the Coverity scan badge as it doesn't render anymore as their domain as an invalid TLS certificate (and the content seems to have moved anyway).

readme.md

@@ -1,6 +1,6 @@
 # SQL LocalDB Wrapper
 
-[![Build Status](https://img.shields.io/appveyor/ci/martincostello/sqllocaldb/master.svg)](https://ci.appveyor.com/project/martincostello/sqllocaldb) [![Coverage Status](https://coveralls.io/repos/martincostello/sqllocaldb/badge.svg?branch=master)](https://coveralls.io/r/martincostello/sqllocaldb?branch=master) [![Coverity Scan Build Status](https://scan.coverity.com/projects/2424/badge.svg)](https://scan.coverity.com/projects/2424)
+[![Build Status](https://img.shields.io/appveyor/ci/martincostello/sqllocaldb/master.svg)](https://ci.appveyor.com/project/martincostello/sqllocaldb) [![Coverage Status](https://coveralls.io/repos/martincostello/sqllocaldb/badge.svg?branch=master)](https://coveralls.io/r/martincostello/sqllocaldb?branch=master)
 
 <!--[![Open GitHub Issues](https://img.shields.io/github/issues/martincostello/sqllocaldb.svg?label=Open%20Issues)](https://github.com/martincostello/sqllocaldb/issues) [![Latest GitHub Release](https://img.shields.io/github/release/martincostello/sqllocaldb.svg?label=Latest%20Release)](https://github.com/martincostello/sqllocaldb/releases/latest) [![License](https://img.shields.io/github/license/martincostello/sqllocaldb.svg?label=License)](https://github.com/martincostello/sqllocaldb/blob/master/license.txt)-->