Re-enable Windows CI (backport #10282)

[mergify]

This PR disables the 9.0.2 validate job for Windows and provides --io-manager=native for every other GHC. See #9571 for the reasons.

---

This is an automatic backport of pull request #10282 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 4aade2d has failed:

On branch mergify/bp/3.12/pr-10282
Your branch is up to date with 'origin/3.12'.

You are currently cherry-picking commit 4aade2d8a.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   .github/workflows/validate.yml

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   cabal-testsuite/PackageTests/Backpack/Includes3/cabal-external.test.hs
	both modified:   validate.sh

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[geekosaur]

Worth noting: validate.yml should have had a merge conflict because the type of the exclusion list changed, but the first line that would have caused it was just outside the context that the merge uses. The result was GHA almost silently dropping the validate job. (GHA's diagnostics for invalid workflows leaves something to be desired.)

[geekosaur]

So now we can't commit the Windows CI fixes to 3.12 because of the Hackage roundtrip tests, and we can't commit the Hackage roundtrip tests workaround to 3.12 because it needs the Windows CI fixes.

[geekosaur]

Cherry-picked into the Hackage round-trip backport.

[geekosaur]

Sorry, per above this needs to stay closed and I need to cherrypick the other Windows fixes.