chore(deps): update sap/project-piper-action action to v1.21.0

Author: renovate[bot]

.github/workflows/open-source-security.yml

@@ -16,13 +16,13 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: artifactPrepareVersion
-        uses: SAP/project-piper-action@v1.20.0
+        uses: SAP/project-piper-action@v1.21.0
         with:
           step-name: artifactPrepareVersion
           flags: --versioningType cloud_noTag
 
       - name: detectExecuteScan
-        uses: SAP/project-piper-action@v1.20.0
+        uses: SAP/project-piper-action@v1.21.0
         with:
           step-name: detectExecuteScan
           flags: '--token ${{ secrets.DETECT_TOKEN }}'