[PATCH kexec-tools] workflow: update to use checkout at v4

[Simon Horman]

On Fri, Feb 02, 2024 at 09:55:41AM +0100, Simon Horman wrote:
> Update to use checkout at v4.
> 
> This addresses the following warning that appears in GitHub runs:
> 
> "Node.js 16 actions are deprecated. Please update the following actions
>  to use Node.js 20: actions/checkout at v3. For more information
>  see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.
> 
> Link: https://github.com/horms/kexec-tools/actions/runs/7753454923
> Signed-off-by: Simon Horman <horms at kernel.org>

Applied.

- workflow: update to use checkout at v4
  https://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git/commit/?id=6ee2ac1bf739