Try updating Github action to v3, since v2 was long-since deprecated

[PhilMiller]

Changes

• Switch from checkout@v2 to checkout@v3

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows project standards (link if applicable)
• Passes all existing automated tests
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future todos are captured in comments
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)
• Reviewers requested with the Reviewers tool ➡️

[PhilMiller]

Before this PR
https://github.com/NOAA-OWP/ngen/actions/runs/5789781100?pr=606

And no warnings with it

[robertbartel]

The only thing that caught my eye was an additional reference to checkout@v2 in .github/workflows/anchor_containerized_test.yml.disabled. I won't object to leaving it out, but thought I'd mention it.

[PhilMiller]

I figured I wasn't going to touch disabled code that I didn't have some familiarity with. Want me to change that one too?

[robertbartel]

@PhilMiller, no, I think it's fine. I can see arguments either way (and I'd probably go back and forth on what I'd do, depending on when I'm asked), but here I was more being extra thorough in case it was accidentally not noticed, rather than consciously left out.