[gitlab-ci] increment package.json version from gitlab-ci + commit & push from a specific branch (after MR). SSH_PRIVATE_KEY variable must be defined as deploy key & CI variable

gitlab-ci.yml

stages:
  - versioning

versioning:
  stage: versioning
  image:
    name: amazonlinux:latest
    entrypoint: [""]
  before_script:
    - yum install -y jq git
    - cd $HOME
    - git config --global user.email "gitlab@$CI_SERVER_HOST"
    - git config --global user.name "gitlab"
    - echo "$SSH_PRIVATE_KEY" > $HOME/private.key && chmod 400 $HOME/private.key
    - mkdir -p ~/.ssh && touch ~/.ssh/known_hosts && ssh-keyscan -p $CI_SERVER_SHELL_SSH_PORT -t rsa $CI_SERVER_HOST >> ~/.ssh/known_hosts
    - git clone -c core.sshCommand="ssh -i $HOME/private.key" "ssh://git@$CI_SERVER_HOST:$CI_SERVER_SHELL_SSH_PORT/$CI_PROJECT_PATH.git" temp && cd temp 
    - git config --add --local core.sshCommand "ssh -i $HOME/private.key"
    - git checkout $CI_COMMIT_BRANCH
  script:
    - cd $HOME/temp
    - export OLD_VERSION=$(jq -r '.version' package.json)
    - cat <<< $(jq '.version = (.version | split(".") | .[0] + "." + .[1] + "." + (.[2] | tonumber+1 | tostring))'  package.json) > package.json
    - export NEW_VERSION=$(jq -r '.version' package.json)
    - echo "bump $OLD_VERSION to $NEW_VERSION"
    - git add .
    - git commit -am "bump version $NEW_VERSION"
    - git push origin $CI_COMMIT_BRANCH
  environment:
    name: staging
  rules:
    - if: '$CI_COMMIT_MESSAGE =~ /^bump version/i'
      when: never
    - if: '$CI_COMMIT_BRANCH == "master" && $CI_PIPELINE_SOURCE == "push" && $CI_COMMIT_MESSAGE !~ /bump version/'