Updates buildpack.toml with 3.2.6

[paketo-bot]

No description provided.

[jmonteiro]

@robdimsdale sorry for the ping, but this PR seems to be "stuck".

The last Ruby version we have is 3.3.5 which was released on Sep 3, 2024 and got the buildpack.toml updated on the same day on this PR.

However since Oct 30, 2024 when Ruby 3.2.6 was released and this PR was open, paketo-bot and paketo-bot-reviewer aren't automatically moving this forward. Although I couldn't understand what's up here (maybe there was a breaking change on GitHub Actions/Workflow?), otherwise I'd propose a fix for it.

This PR have been updated since that, hence why we have from Ruby 3.2.6 to Ruby 3.3.8 (latest on 3.3.x) all commited here.

We're also behind with Ruby 3.4, which was released on Dec 25, 2025 but is still not available here. I see that people proposed updating it manually on #953

[jmonteiro]

cc @sophiewigmore as you also worked on this repo in the past :-)

[jmonteiro]

cc @arjun024 as you have worked on this repo in the past :-)