ospack: pass timestamp needed by image_version

Signed-off-by: Héctor Orón Martínez <hector.oron@collabora.co.uk>

Jenkinsfile

@@ -44,6 +44,7 @@ def buildImage(architecture, type, board, debosarguments = "", sysroot = false,
                     -t type:${type} \
                     -t architecture:${architecture} \
                     -t suite:${release} \
+                    -t timestamp:${PIPELINE_VERSION} \
                     -t ospack:ospack_${release}-${architecture}-${type}_${PIPELINE_VERSION}.tar.gz \
                     ${WORKSPACE}/apertis-ospack.yaml""")
               }