ci: remove ssh-keyscan command that doesn't exist in Alpine Linux

Fix CI failure caused by missing ssh-keyscan command in Alpine Linux.

Problem:
- ssh-keyscan command not available in node:20-alpine image
- This caused CI to fail with '/bin/sh: ssh-keyscan: not found'

Solution:
- Remove ssh-keyscan command as it's not essential for SSH connection
- SSH will automatically handle host key verification

This should resolve the final CI failure and allow successful deployment.

.woodpecker.yml

@@ -131,7 +131,6 @@ steps:
       - mkdir -p ~/.ssh
       - echo "$SSH_PRIVATE_KEY" > ~/.ssh/id_rsa
       - chmod 600 ~/.ssh/id_rsa
-      - ssh-keyscan -H 139.155.109.62 >> ~/.ssh/known_hosts
       - echo "Pre-deployment checks"
       - ssh root@139.155.109.62 "echo 'Server connection OK'"
       - ssh root@139.155.109.62 "df -h | grep -E '/$|/home'"