feat: 3.0.0-beta2 release.

Author: jrfaller

build.gradle

@@ -6,7 +6,7 @@ allprojects {
     apply plugin: 'idea'
 
     group = 'com.github.gumtreediff'
-    version = '3.0.0-SNAPSHOT'
+    version = '3.0.0-beta2'
 
     repositories {
         mavenCentral()