update: remove pre-3 from version

Author: FllipEis

build.gradle

@@ -29,7 +29,7 @@ plugins {
 allprojects {
 
     group 'eu.thesimplecloud.simplecloud'
-    version '2.8.0-pre.3'
+    version '2.8.0'
 
     repositories {
         mavenCentral()