use branch_tip instead of forgejo-test-helper.sh output

testdata/nested-upload-download/.forgejo/workflows/test.yml

@@ -20,8 +20,9 @@ jobs:
           image-version: 1.20
       - id: testrepo
         run: |
-          forgejo-test-helper.sh push testrepo http://testuser:admin1234@${{ steps.forgejo.outputs.host-port }} testuser testrepo > /tmp/output
-          grep '^sha=' < /tmp/output >> $GITHUB_OUTPUT
+          url=http://testuser:admin1234@${{ steps.forgejo.outputs.host-port }}
+          forgejo-test-helper.sh push testrepo $url testuser testrepo > /tmp/output
+          echo sha=$(forgejo-test-helper.sh branch_tip $url testuser/testrepo main) >> $GITHUB_OUTPUT
       - id: release-upload
         uses: SELF@vTest
         with: