Exclude 5.9 workflows and enable macOS testing scheme for CI

Author: phausler

.github/workflows/pull_request.yml

@@ -9,6 +9,9 @@ jobs:
     name: Test
     uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
     with:
+      linux_exclude_swift_versions: "[{\"swift_version\": \"5.9\"}]"
+      windows_exclude_swift_versions: "[{\"swift_version\": \"5.9\"}]"
+      enable_macos_checks: true
       enable_wasm_sdk_build: true
       wasm_sdk_build_command: swift build -Xcc -D_WASI_EMULATED_PTHREAD