string `DONE` has 3 occurrences, make it a constant (goconst)

issues found

Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v3, actions/setup-go@v4, golangci/golangci-lint-action@v3. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.