Add Version 3.0 to versions

src/main/scala/gitbucket/core/servlet/InitializeListener.scala

@@ -21,6 +21,7 @@ object AutoUpdate {
    * The history of versions. A head of this sequence is the current BitBucket version.
    */
   val versions = Seq(
+    new Version(3, 0),
     new Version(2, 8),
     new Version(2, 7) {
       override def update(conn: Connection, cl: ClassLoader): Unit = {