Replace actions/checkout@v3 -> actions/checkout@v4

[katayama8000]

I replaced actions/checkout@v3 with actions/checkout@v4.

[CLAassistant]

All committers have signed the CLA.

[magurotuna]

Thanks for catching this. Of course this change looks totally good, but another issue is happening where deployctl's dependency depends on Deno.isatty which was removed from Deno v2.0. I'll try to fix this first and then will merge your PR.

[katayama8000]

@magurotuna Thanks :)