Update triage-party to fix the "similar" bug

[maelvls]

One annoying thing I noticed yesterday while triaging on https://triage.build-infra.jetstack.net is that the similar label appears sometimes more than 50 times:

The issue, tracked in google/triage-party#196, has been solved in google/triage-party#204 and contained in Triage Party v1.3.0. We are using Triage Party v1.2.1. I searched for an upgrade process but there does not seem to be one, since Triage Party seems to rely on a cache that can be reconstructed after the upgrade.