remove amazonlinux2 checkouts

[madrob]

AmazonLinux2 was removed from testing in #298 we should also remove the conditional use of checkout@v1 action.

[shahmishal]

We have not removed it from checkout support yet because repositories might still test Amazon Linux 2 with older Swift releases.

[madrob]

What's that going to be gated on? https://www.swift.org/platform-support/ doesn't distinguish by Swift version.

[shahmishal]

What's that going to be gated on? https://www.swift.org/platform-support/ doesn't distinguish by Swift version.

https://github.com/swiftlang/project-operations/blob/main/github-policies.md

• Packages should support the latest patch releases of the last three minor official Swift releases.
  • For example, if the currently latest Swift release is 6.2.1 then a package would be expected to support 6.2.1, 6.1.3 and 6.0.3.
  • As an exception, new packages are free to start with only supporting the latest official Swift release.

[madrob]

That answers half the question, but not "which versions of Swift need to run on AmazonLinux 2?"

I think it's everything <= 6.3, but I don't see that written. So the implication is that we would be able to merge this PR after Swift 6.6 is released?