gitlab ci push changes to protected branch using node.js

.gitlab-ci.yml

grunt:
  only:
    - master
  script:
    - 'git checkout -b CI${CI_JOB_ID}'
    #make changes on local repo
    - 'git add . || true'
    - 'git commit -a -m "[ci skip] build" || true'
    - 'git push https://<username>:<token>@gitlab.com/<team>/<project>.git HEAD:CI${CI_JOB_ID} || true'
    - 'node ./mergeBranch.js CI${CI_JOB_ID}'

mergeBranch.js

"use strict";
const request = require('request-promise');
const Promise = require('bluebird');

const gitlabToken = "<TOKEN>";
const projectId = "<PROJECT_ID>";
const baseUrl = "https://gitlab.com/api/v4/";
const asigneeId = <ASSIGNEE_ID>;
const targetBranch = "master";

const args = process.argv.slice(2);
const branch = args[0];

if (!branch) {
  console.error('no branch provided');
  process.exit(1);
}

const createPR = {
  method: "POST",
  headers: {
    "PRIVATE-TOKEN": gitlabToken
  },
  json: true,
  body: {
    source_branch: branch,
    target_branch: targetBranch,
    assignee_id: asigneeId,
    remove_source_branch: true,
    title: branch,
    squash: true,
    allow_maintainer_to_push: true
  },
  url: baseUrl + "projects/" + projectId + "/merge_requests"
};

function createPullRequest() {
  console.log("creating pull request", branch);
  return request(createPR)
    .then(function (result) {
      const prid = result.iid;
      console.log("pull request created", prid);
      console.log("merging pull request");
      const mergePR = {
        method: "PUT",
        headers: {
          "PRIVATE-TOKEN": gitlabToken
        },
        json: true,
        body: {
          should_remove_source_branch: true,
          merge_when_pipeline_succeeds: false,
          merge_commit_message: '[ci skip] ci build'
        },
        url: baseUrl + "projects/" + projectId + "/merge_requests/" + prid + "/merge"
      };
      return request(mergePR);
    });
}

createPullRequest()
  .then(function () {
    console.log("pull request merged");
    process.exit(0);
  })
  .catch(function (err) {
    console.log("failed", err.error.message);
    process.exit(1);
  });