try chmoding key

ci/push-package.template.yml

@@ -6,7 +6,7 @@
       - 'command -v ssh-agent >/dev/null || ( apt-get update -y && apt-get install openssh-client -y )'
       - eval $(ssh-agent -s)
       - chmod 400 "$SSH_PRIVATE_KEY"
-      - echo "$SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add -
+      - ssh-add "$SSH_PRIVATE_KEY"
       - chmod 700 ~/.ssh
       - '[[ -f /.dockerenv ]] && echo -e "Host *\\n\\tStrictHostKeyChecking no\\n\\n" > ~/.ssh/config'
     script: