CI: add tests for Windows

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

.github/workflows/ci.yml

@@ -2,7 +2,7 @@ name: CI
 on:
   - push
 jobs:
-  test:
+  linux:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
@@ -19,3 +19,24 @@ jobs:
         run: zig build test
       - name: webgpu::test
         run: cd webgpu && zig build test
+  windows:
+    runs-on: windows-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Install Git
+        run: choco install git
+      - name: Setup Zig
+        run: |
+          Invoke-WebRequest -Uri "https://ziglang.org/builds/zig-windows-x86_64-0.9.0-dev.441+7b5d139fd.zip" -OutFile "C:\zig.zip"
+          cd C:\
+          7z x zig.zip
+          Add-Content $env:GITHUB_PATH "C:\zig-windows-x86_64-0.9.0-dev.441+7b5d139fd\"
+      - name: mach::test cross Windows->MacOS
+        run: zig build test -Dtarget=x86_64-macos
+        env:
+          AGREE: true
+      - name: mach::test
+        run: zig build test
+      - name: webgpu::test
+        run: cd webgpu && zig build test