Enable Windows tests in GitHub Actions

Fixes #2992

Author: ahoppen

.github/workflows/pull_request.yml

@@ -8,9 +8,6 @@ jobs:
   tests:
     name: Test
     uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
-    with:
-      # https://github.com/swiftlang/swift-syntax/issues/2992
-      enable_windows_checks: false
   soundness:
     name: Soundness
     uses: swiftlang/github-workflows/.github/workflows/soundness.yml@main