Run this script in console of '/labels' endpoint of a repository

githubLabels.js

[
  {
    "name": "server",
    "color": "5319e7"
  },
  {
    "name": "bug",
    "color": "ee0701"
  },
  {
    "name": "data",
    "color": "fbca04"
  },
  {
    "name": "duplicate",
    "color": "cccccc"
  },
  {
    "name": "enhancement",
    "color": "84b6eb"
  },
  {
    "name": "frontend",
    "color": "1d76db"
  },
  {
    "name": "help wanted",
    "color": "128A0C"
  },
  {
    "name": "in-progress",
    "color": "009688"
  },
  {
    "name": "in-review",
    "color": "006b75"
  },
  {
    "name": "invalid",
    "color": "e6e6e6"
  },
  {
    "name": "please-test",
    "color": "08e700"
  },
  {
    "name": "priority-1",
    "color": "0d47a1"
  },
  {
    "name": "priority-2",
    "color": "1976d2"
  },
  {
    "name": "priority-3",
    "color": "42a5f5"
  },
  {
    "name": "priority-4",
    "color": "bbdefb"
  },
  {
    "name": "priority-5",
    "color": "bbdefb"
  },
  {
    "name": "question",
    "color": "cc317c"
  },
  {
    "name": "T1d",
    "color": "e91e63"
  },
  {
    "name": "T1h",
    "color": "fce4ec"
  },
  {
    "name": "T2d",
    "color": "e91e63"
  },
  {
    "name": "T2h",
    "color": "f06292"
  },
  {
    "name": "T3d",
    "color": "e91e63"
  },
  {
    "name": "T4d",
    "color": "e91e63"
  },
  {
    "name": "T4h",
    "color": "f06292"
  },
  {
    "name": "T5d",
    "color": "e91e63"
  },
  {
    "name": "T6h",
    "color": "f06292"
  },
  {
    "name": "T30m",
    "color": "fce4ec"
  },
  {
    "name": "technical",
    "color": "D4C5F9"
  },
  {
    "name": "UI",
    "color": "207de5"
  },
  {
    "name": "wontfix",
    "color": "ffffff"
  }
].forEach(function(label) {
  addLabel(label)
})

function updateLabel (label) {
  var flag = false;
  [].slice.call(document.querySelectorAll(".labels-list-item"))
  .forEach(function(element) {
    if (element.querySelector('.label-link').textContent.trim() === label.name) {
      flag = true
      element.querySelector('.js-edit-label').click()
      element.querySelector('.label-edit-name').value = label.name
      element.querySelector('.color-editor-input').value = '#' + label.color
      element.querySelector('.new-label-actions .btn-primary').click()
    }
  })
  return flag
}

function addNewLabel (label) {
  document.querySelector('.new-label input#label-').value = label.name
  document.querySelector('.new-label input#edit-label-color-new').value = '#' + label.color
  document.querySelector('.new-label-actions .btn-primary').click()
}

function addLabel (label) {
  if (!updateLabel(label)) addNewLabel(label)
}