actions: Fix Windows Go version

Prior to this patch, the Go version for the Windows tests in Github
resolved to `1.15.15`[1].

With this patch, the Go version for the Windows tests is fixed to
actually resolve to the latest version (^1.16), consistent to the other
platforms.

This patch also bumps `actions/setup-go`[2] to the latest version,
consistent with the other platforms.

[1]: https://github.com/kubernetes-csi/csi-driver-nfs/runs/4211323920?check_suite_focus=true
[2]: https://github.com/actions/setup-go

.github/workflows/windows.yaml

@@ -6,14 +6,14 @@ jobs:
   build:
     strategy:
       matrix:
-        go-versions: [1.16.x]
+        go: [ '^1.16' ]
         platform: [windows-latest]
     runs-on: ${{ matrix.platform }}
     steps:
       - name: Install Go
-        uses: actions/setup-go@v1
+        uses: actions/setup-go@v2
         with:
-          go-version: ${{ matrix.go-version }}
+          go-version: ${{ matrix.go }}
       - name: Checkout code
         uses: actions/checkout@v2
       - name: Run Windows Unit Tests