Convert seconds to minutes and hours on chat notifations

From the commit message

Convert seconds to minutes and hours on chat notifations

In the pipeline message, the duration of the pipeline was shown as:

gitlab-org/gitlab-ee: Pipeline #8002259 of master branch by Douwe Maan failed in 8612 seconds

But this many seconds only gave me a clue how long the pipeline took, so now this will be shown as something like: 02:20:12 which gives a much better measure of time.