feat: add flutter-version datasource

[zeshuaro]

Changes

• Add Flutter datasource
• Issue suggested to use this link to fetch the Flutter releases https://storage.googleapis.com/flutter_infra/releases/releases_linux.json. But it's no longer updated and the new link seems to be this one instead https://storage.googleapis.com/flutter_infra_release/releases/releases_linux.json

Context

Close #12820

Documentation (please check one with an [x])

• I have updated the documentation, or
• No documentation update is required (not sure if I need to add a README for this new datasource)

How I've tested my work (please tick one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• Both unit tests + ran on a real repository

[zeshuaro]

I included the full API response for the test, not sure if we need it or a subset of it would be sufficient.

[rarkins]

Is this datasource for the version of Flutter itself? For other similar ones we use a -version suffix to try to avoid confusion, e.g.

[viceice]

You can apply all suggestions as batch from github review page 😉

[zeshuaro]

Thanks for sharing the batch commit trick, I didn't know we can do that on GitHub.

So after these changes are merged, I assume this would unblock two other issues related to update the pubspec.lock file. I can see that you already have a PR up in the buildpack repo, will you have time to follow-up on that work? Otherwise, I'm happy to help out as well.

[viceice]

nearly done

[renovate-release]

🎉 This PR is included in version 32.10.0 🎉

The release is available on:

• GitHub release
• 32.10.0

Your semantic-release bot 📦🚀