precommithook: yamllint toegevoegd op drone.yml

githooks/pre-commit

@@ -1,6 +1,7 @@
-#!/bin/sh
+#!/bin/sh -e
 VERSION=$(grep version setup.py | sed -e 's/.*="//' -e 's/",//')
 sed -i "s/^__version__ = .*/__version__ = '${VERSION}'/"  ddOperApi/__init__.py
 git add ddOperApi/__init__.py
 
 python setup.py test
+yamllint .drone.yml