Fixed job control in .gitlab-ci.yml

deploy:

    stage: deploy

    rules:

        - if: '"$DEPLOY_SSH_KEY" != "" && "$CI_COMMIT_REF_NAME" == "$CI_DEFAULT_BRANCH"'

    only:

        refs:

            - main

        variables:

            - $DEPLOY_SSH_KEY

            - $DEPLOY_HOSTKEY

    script:

        # Set up SSH

        - eval $(ssh-agent -s)