ci: use PAT auth for Scout Docker Hub login

[crazy-max]

relates to https://github.com/docker/buildx/actions/runs/31011492529/job/92329179778#step:3:211

/usr/bin/docker scout cves registry://docker/buildx-bin:master --format sarif --output /home/runner/work/_temp/docker-scout-9e5R4q/result.txt
      i New version 1.24.0 available (installed version is 1.11.0) at https://github.com/docker/scout-cli
        Log in with your Docker ID or email address to use docker scout.
  
  If you don't have a Docker ID, head over to https://hub.docker.com/ to
  create one. You can log in with your password or a Personal Access Token (PAT)
  by running docker login.
  Using a limited-scope PAT grants better security and is required for organizations
  using SSO. Learn more at https://docs.docker.com/go/access-tokens/
  
  You can also log in using Docker Desktop.

OIDC doesn't seem supported by Scout at the moment.