Fix scorecard action: pin to v2.4.3 (v2 tag removed)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: vitbokisch

.github/workflows/security.yml

@@ -73,7 +73,7 @@ jobs:
           persist-credentials: false
 
       - name: Run Scorecard
-        uses: ossf/scorecard-action@v2
+        uses: ossf/scorecard-action@v2.4.3
         with:
           results_file: results.sarif
           results_format: sarif