fix(ci): decode ssh key from base64

.gitlab-ci.yml

@@ -31,7 +31,7 @@ prepare:
   before_script:
     - apk add --no-cache git openssh
     - eval `ssh-agent -s`
-    - echo "${SSH_PRIVATE_KEY}" | tr -d '\r' | ssh-add - > /dev/null
+    - echo "$SSH_PRIVATE_KEY" | openssl enc -d -base64 | tr -d '\r' | ssh-add -
     - mkdir -p ~/.ssh
     - chmod 700 ~/.ssh
     - '[[ -f /.dockerenv ]] && echo -e "Host *\n\tStrictHostKeyChecking no\n\n" > ~/.ssh/config'