Make the base branch master instead of develop (#72)

We already open the pr's to update docker images against master,
hence we should not use develop as the base branch.

Author: onurctirtir

automated_packaging/update_docker.pl

@@ -18,7 +18,7 @@
 $curTime = time();
 
 # Checkout to the release's branch
-`git checkout develop`;
+`git checkout master`;
 `git checkout -b release-$VERSION-$curTime`;
 
 # That means we want to update postgres version