Added kleidukos/get-tested action to generate CI matrix #64

[DavidMazarro]

Thanks to the get-tested action, we can automatically generate the matrix of GHC versions to run the CI on. This keeps the tested-with versions we set in Cabal files accurate to what is actually being tested in the CI.

Since the action takes one Cabal file as reference, I pointed it to rollbar-client.cabal since that is the main library in this repository. In any case, us maintainers need to keep all of the tested-with versions in sync across the four Haskell packages we offer in this repository.

This PR also changes the tested-with versions of the Cabal in the project to the latest minor versions of GHC 8.10 (the latest GHC 8 version), GHC 9.6 and GHC 9.8 (the two most recent GHC 9 versions).

Closes #189.

[DavidMazarro]

In addition to the GHC versions found in the tested-with, since we also had a manual GHC 9.2 version with a macos-latest runner, I tried including that too. However, from the research I've done it looks like GitHub Actions doesn't support the addition of runners to dynamically generated matrices, so I couldn't do it with by using includes. I couldn't find an easy way to extend the generated JSON either, I found some examples online but they envolved a mix of tricks with different commands and jq. If anyone knows how we could add the GHC 9.2 + macOS runner to the matrix generated by the get-tested action, let me know.

That said, should consider if we want to add the macos-latest runner to the matrix generation, which means it would run on all GHC versions. I believe macOS runners are also free for open source repositories. So unless the pricing is different for open source repos under organizations, it shouldn't cost us any extra to spin up a macos-latest runner for all of the GHC versions instead of just one, and we wouldn't have to keep track and update that isolated version in our CI workflow. Let me know your thoughts on this 🙂

[CristhianMotoche]

Hi @DavidMazarro Thank you so much for working on this! We already have 5 ubuntu instances running. If we add macos to the matrix that will be 10. It seems a little bit too much. Let's look for an easy way to run macos for the last version of GHC. If we don't find one then we may want to keep the previous set up.

[DavidMazarro]

After discussing internally, we have decided that we will keep parity between Ubuntu and macOS runners, and we will be cutting the amount of GHC versions we test with. I updated the PR description with more details.

[CristhianMotoche]

LGTM!