Fix SSH known_hosts configuration in GitLab CI

.gitlab-ci.yml

@@ -15,7 +15,7 @@ deploy_to_production:
     - echo "$SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add -
     - mkdir -p ~/.ssh
     - chmod 700 ~/.ssh
-    - echo "$SSH_PRIVATE_KEY" > ~/.ssh/known_hosts
+    - echo "$SSH_KNOWN_HOSTS" > ~/.ssh/known_hosts
     - chmod 644 ~/.ssh/known_hosts
   script:
     - echo "Starting production deployment"