ci: update version of checkout action

Fix the following warning:

NO_WRAP
    Node.js 12 actions are deprecated. For more information see:
    https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/.
    Please update the following actions to use Node.js 16: actions/checkout
NO_WRAP

Fixes tarantool/tarantool-qa#279

NO_DOC=ci
NO_TEST=ci
NO_CHANGELOG=ci