Update .github/workflows/security-dependencies-check.yml

Co-authored-by: Copilot <[email protected]>

Author: sthulb

.github/workflows/security-dependencies-check.yml

@@ -37,4 +37,4 @@ jobs:
         uses: actions/dependency-review-action@3b139cfc5fae8b618d3eae3675e383bb1769c019 # v4.5.0
         with:
           config-file: './.github/dependency-review-config.yml'
-          head-ref: ${{ github.ref }}
+          head-ref: ${{ github.event_name == 'pull_request' && github.head_ref || github.ref_name }}