Create windows.yml (#22)

* Create windows.yml

* Update windows.yml

.github/workflows/windows.yml

@@ -0,0 +1,20 @@
+name: Windows
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+jobs:
+  build:
+    runs-on: windows-latest
+    steps:
+      - uses: compnerd/gha-setup-swift@main
+        with:
+          branch: swift-5.9-release
+          tag: 5.9-RELEASE
+
+      - uses: actions/checkout@v2
+      - run: swift build
+      - run: swift test