Update snyk-container.yml

[ci skip]

Author: patrikjuvonen

.github/workflows/snyk-container.yml

@@ -50,7 +50,7 @@ jobs:
         image: patrikjuvonen/docker-nginx-http3:snyk-ci
         args: --file=Dockerfile
     # Patch for https://github.com/github/codeql-action/issues/2187
-    - name: Replace security-severity undefined for license-related findings
+    - name: Replace null security-severity for license-related findings
       run: |
         sed -i 's/"security-severity": "null"/"security-severity": "0"/g' snyk.sarif
     - name: Upload result to GitHub Code Scanning