[CI] GitHub Actions - Support macOS testing

Author: shahmishal

.github/workflows/pull_request.yml

@@ -22,6 +22,7 @@ jobs:
       windows_build_command: 'Invoke-Program swift test --no-parallel'
       enable_linux_static_sdk_build: true
       linux_static_sdk_build_command: SWIFTBUILD_STATIC_LINK=1 LLBUILD_STATIC_LINK=1 swift build
+      enable_macos_checks: true
   cmake-smoke-test:
     name: cmake-smoke-test
     uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main