Tests: Fix test data
Tests: Fix test data

Fixes format of a mocked message used in tests. Correct format is
explained in CI Messages documentation at [1].

[1] https://pagure.io/fedora-ci/messages

Signed-off-by: Lukas Holecek <9242296069c25c30688bbce328d352a7320fa926@email.cz>

release-engineering/resultsdb-updater,release-engineering/resultsdb-updater