make-snapshot.sh: Make sure ipl parts are properly updated

bin/make-snapshot.sh

@@ -22,6 +22,9 @@ git checkout -b $BRANCH
 git merge --no-ff -m "Merge latest tag, to make it reachable for git-describe" $LATEST_TAG
 
 composer config platform.php $PHP_VERSION
+composer config minimum-stability dev
+composer config prefer-stable true
+
 composer require --no-update \
   php:$PHP_VERSION \
   ipl/html:"dev-master as 99.x-dev" \