ci: updates branch name strategy

fixes #24866

Signed-off-by: Ramon Roche <mrpollo@gmail.com>

.github/workflows/build_all_targets.yml

@@ -54,7 +54,13 @@ jobs:
         run: echo "::set-output name=timestamp::$(date +"%Y%m%d%H%M%S")"
 
       - id: set-branch
-        run: echo "::set-output name=branchname::${GITHUB_HEAD_REF:-${GITHUB_REF#refs/heads/}}"
+        run: |
+          echo "branchname=${{
+            github.event_name == 'pull_request' &&
+            format('pr-{0}', github.event.pull_request.number) ||
+            github.head_ref ||
+            github.ref_name
+          }}" >> $GITHUB_OUTPUT
 
       - name: Debug Matrix Output
         if: runner.debug == '1'