check-for-missing-dlls: also run on pushes to the ucrt64 branch

Same reasoning as the matching change to `ci-artifacts.yml`: while the
PR opened from this branch (#117) is in a `DIRTY` merge state, GitHub
refuses to dispatch `pull_request` events, so the DLL check no longer
runs against the PR head. Listing `ucrt64` under the `push` trigger
restores coverage directly from the branch tip.

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

Author: dscho

.github/workflows/check-for-missing-dlls.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - main
+      - ucrt64
   pull_request:
 
 env: