fix(snyk): replace security-severity null for license-related findings

.github/workflows/snyk_container-analysis.yml

@@ -56,9 +56,9 @@ jobs:
           image: sjmayotte/route53-dynamic-dns
           args: --file=Dockerfile
         # Related to snyk issue: https://github.com/github/codeql-action/issues/2187
-      - name: Replace security-severity undefined for license-related findings
+      - name: Replace security-severity null for license-related findings
         run: >
-          sed -i 's/"security-severity": "undefined"/"security-severity": "0"/g' snyk.sarif
+          sed -i 's/"security-severity": "null"/"security-severity": "0"/g' snyk.sarif
       - name: Upload result to GitHub Code Scanning
         uses: github/codeql-action/upload-sarif@v3
         with: