Update actions/checkout action to v4

This PR contains the following updates:

Package	Type	Update	Change
actions/checkout	action	major	`v3` -> `v4`

Release Notes

actions/checkout (actions/checkout)

### [`v4`](https://redirect.github.com/actions/checkout/blob/HEAD/CHANGELOG.md#v421) [Compare Source](https://redirect.github.com/actions/checkout/compare/v3...v4) - Check out other refs/\* by commit if provided, fall back to ref by [@orhantoy](https://redirect.github.com/orhantoy) in [https://github.com/actions/checkout/pull/1924](https://redirect.github.com/actions/checkout/pull/1924)

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rpc404 / playpoint-user

Update actions/checkout action to v4 #256

Release Notes

Configuration