Update update script

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

lib/scripts/update.sh

@@ -16,14 +16,16 @@ for path in ${paths}; do
   echo "Processing submodule: ${path}"
 
   cd "${path}" || exit
-  git checkout master
-  git fetch upstream
-  git merge upstream/master
 
-  branches=$(git for-each-ref --format='%(refname:short)' refs/heads/ | grep -v '^master$')
+  default_branch=$(git remote show origin | awk '/HEAD branch/ {print $NF}')
+  git checkout "${default_branch}"
+  git fetch upstream
+  git merge "upstream/${default_branch}"
+
+  branches=$(git for-each-ref --format='%(refname:short)' refs/heads/ | grep -v "^${default_branch}$")
   for branch in ${branches}; do
     git checkout "${branch}"
-    git rebase master
+    git rebase "${default_branch}"
   done
 
   git checkout integration