Fix failing build do to a grgit/jgit issue

Fixes #288

(cherry picked from commit c92478f)

Author: cboehme

build.gradle

@@ -17,7 +17,7 @@
 import java.util.regex.Matcher
 
 plugins {
-  id 'org.ajoberstar.grgit' version '2.0.1'
+  id 'org.ajoberstar.grgit' version '2.3.0'
   id 'org.sonarqube' version '2.5'
   id 'io.codearte.nexus-staging' version '0.11.0'
   id "org.standardout.versioneye" version "1.5.0"