Allow the ClamAV image through the dockerhub remote

The mail namespace runs clamd + freshclam from clamav/clamav on Docker Hub
via the artifactapi mirror. Add it to the dockerhub allowlist.

- add "^clamav/clamav" to config/remote_docker/dockerhub.yaml patterns

config/remote_docker/dockerhub.yaml

@@ -16,6 +16,7 @@ patterns:
   - "^library/redis"
   - "^beats/filebeat"
   - "^bitnami/"
+  - "^clamav/clamav"
   - "^clickhouse/"
   - "^curlimages/curl"
   - "^emberstack/kubernetes-reflector"