ci: Test against Windows, Go 1.21, 1.22

Upgrade to Go 1.21, 1.22 since those are the two latest versions.

Plus Fx supports Windows and has tests against it,
so Dig should test against it too.

.github/workflows/go.yml

@@ -13,11 +13,12 @@ permissions:
 jobs:
 
   build:
-    runs-on: ubuntu-latest
-    name: Test (Go ${{ matrix.go }})
+    runs-on: ${{ matrix.os }}
+    name: Test (Go ${{ matrix.go }} / ${{ matrix.os }})
     strategy:
       matrix:
-        go: ["1.20.x", "1.21.x"]
+        os: ["ubuntu-latest", "windows-latest"]
+        go: ["1.21.x", "1.22.x"]
 
     steps:
     - name: Setup Go
@@ -48,7 +49,7 @@ jobs:
     - name: Setup Go
       uses: actions/setup-go@v5
       with:
-        go-version: 1.21.x
+        go-version: 1.22.x
         cache: false  # managed by golangci-lint
 
     - uses: golangci/golangci-lint-action@v3