building-wtfapp-udooneo: Change used Docker image
building-wtfapp-udooneo: Change used Docker image

See https://github.com/gmacario/wtf-docs/pull/24

Signed-off-by: Gianpaolo Macario <f8885408b8c3d931b330bae3c3a28a3af912c463@gmail.com>
gmacario/easy-jenkins