Update README.md

Update status badge to point to Github Workflows

Author: puneetbehl

README.md

@@ -1,4 +1,6 @@
-[![Build Status](https://travis-ci.org/grails/grails-data-mapping.svg?branch=master)](https://travis-ci.org/grails/grails-data-mapping)
+![Java CI](https://github.com/grails/grails-data-mapping/workflows/Java%20CI/badge.svg?branch=master)
+![Release](https://github.com/grails/grails-data-mapping/workflows/Release/badge.svg?branch=master)
+![Maven Central Sync](https://github.com/grails/grails-data-mapping/workflows/Maven%20Central%20Sync/badge.svg?branch=master)
 
 GORM (Grails Object Mapping)
 ===