TestKanikoTaskRun: explicitely run as root 🔦
TestKanikoTaskRun: explicitely run as root 🔦

It seems `kaniko` needs to be run as root to work, so be explicit
about it. This is especially useful on kubernetes distribution that
default to run as user (like OpenShift).

Signed-off-by: Vincent Demeester <b98c0fd48a8945096c766de790fe70420dd2f223@redhat.com>

tektoncd/pipeline,tektoncd/pipeline