fix(ci): move vale action back to use ubuntu-latest / fix vocab dirs

[johncowen]

Back in #1972 following a suggested fix for a python error in the vale GH action, we pinned ubuntu to what seemed like a working version. We've since seen that whilst it looked to be working, there were still errors deeper in the logs that somehow weren't caught by CI.

This PR:

1. Bumps the version of the vale GH action (I'm hoping/assuming this is why these errors weren't caught in CI?)
2. Changes the location of the Base vocabularies as a consequence of the GH action using latest for the version of vale to use i.e. vale version 3.something. The previous location was only supported in vale 2.something. This change fixed an error that has been appearing in CI logs over several PRs.
3. Puts things back to use ubuntu latest

Closes: #1973

---

Previous notes:

PR to experiment with fixes for a vale CI error thats appeared.

Related: #1972

The linked PR looked like it was a good fix (CI passed), but looking deeper into the errors in that passing PR run, showed a similar error that is now making CI fail.

Continuing to experiment/investigate

[netlify]

✅ Deploy Preview for kuma ready!

Name	Link
🔨 Latest commit	ba74bf2
🔍 Latest deploy log	https://app.netlify.com/sites/kuma/deploys/6710e44c1c54f700087c87fa
😎 Deploy Preview	https://deploy-preview-1975--kuma.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.
Lighthouse	1 paths audited Performance: 92 (🟢 up 9 from production) Accessibility: 90 (no change from production) Best Practices: 100 (no change from production) SEO: 85 (no change from production) PWA: 80 (no change from production) View the detailed breakdown and full score reports

---

To edit notification comments on pull requests, go to your Netlify site configuration.