Upgrade Grgit Gradle plugin to version 5.3.3. (#426)

Author: blackwinter

build.gradle

@@ -17,7 +17,7 @@
 import java.util.regex.Matcher
 
 plugins {
-  id 'org.ajoberstar.grgit' version '2.3.0'
+  id 'org.ajoberstar.grgit' version '5.3.3'
   //id 'org.ec4j.editorconfig' version '0.0.3'
   id 'org.sonarqube' version '2.6.2'
   id 'org.xtext.builder' version '4.0.0'