ci-artifacts: also run on pushes to the ucrt64 branch

The PR opened from this branch (#117) keeps diverging from `main` (the
package-sync commits keep landing there, and the conversion commits
keep removing the MINGW64 tree here), so the merge commit GitHub
builds for the `pull_request` event is `DIRTY` most of the time. While
in that state, GitHub skips the `pull_request` workflow dispatch
entirely, which means `ci-artifacts` no longer runs against the PR
head and we lose all signal about whether the converted SDK still
builds Git.

Adding `ucrt64` to the workflow's `push` trigger sidesteps that:
pushes to the branch run the workflow directly, without going through
a synthetic merge commit, so the build/test matrix stays exercised
until the branch is finally merged.

Assisted-by: Opus 4.7
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

.github/workflows/ci-artifacts.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - main
+      - ucrt64
   pull_request:
 
 # For the continuous `ci-artifacts` release