dynamically determine base branch name in mattermost notifications (#10496)

previously, if we merged a PR into one of our point release branches,
the mattermost notification would still say it was merged into main.
this PR fixes that

you can see me testing this change on my fork with this [workflow
file](https://github.com/bmw/letsencrypt/actions/runs/19588662936/workflow#L30)
and this
[output](https://github.com/bmw/letsencrypt/actions/runs/19588662936/job/56102625766#step:2:4)

if this PR is merged, i'll do the same thing in our josepy repo
This commit is contained in:
Brad Warren 2025-11-24 13:42:14 -08:00 committed by GitHub
parent b02deb339a
commit e9050f1a3c
No known key found for this signature in database
GPG key ID: B5690EEEBB952194

View file

@ -27,4 +27,4 @@ jobs:
[${{ github.repository }}] |
[${{ github.event.pull_request.title }}
#${{ github.event.number }}](https://github.com/${{ github.repository }}/pull/${{ github.event.number }})
was merged into main by ${{ github.actor }}
was merged into ${{ github.event.pull_request.base.ref }} by ${{ github.actor }}