Upgrade to Play 3.0

[davidfurey]

What does this change?

Minimal changes to upgrade to Play 3.0. This includes switching from Akka to Pekko.

How can we measure success?

I can upgrade atom-workshop to Play 3.0

[rtyley]

Looks great! This will now need to be rolled out to:

• https://github.com/guardian/atom-workshop
• https://github.com/guardian/media-atom-maker

You could use gha-scala-library-release-workflow to do a 'preview' release of this PR to Maven, and try that out in those repos before merging this PR, but it's probably not necessary!

See also:

• Fix tests under Java 17 (Upgrade to Play 2.9 & update Guice) #94
• Upgrading to Play 3.0 maintaining-scala-projects#4

[gu-scala-library-release]

@davidfurey has published a preview version of this PR with release workflow run #13, based on commit ba68b55:

3.0.0-PREVIEW.play-30.2024-03-12T1559.ba68b556

Want to make another preview release?

Click 'Run workflow' in the GitHub UI, specifying the play-3.0 branch, or use the GitHub CLI command:

gh workflow run release.yml --ref play-3.0

Want to make a full release after this PR is merged?

Click 'Run workflow' in the GitHub UI, leaving the branch as the default, or use the GitHub CLI command:

gh workflow run release.yml

[davidfurey]

Thanks Roberto. I've published a preview version, and it works in atom-workshop.