ci: update go.yml workflow file and setup-go version

- Update the `go.yml` workflow file
- Change the `actions/setup-go` version from v3 to v4
- Add `1.21` as a valid value for the `go` matrix variable

Signed-off-by: Bo-Yi Wu <[email protected]>

.github/workflows/go.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Setup go
-        uses: actions/setup-go@v3
+        uses: actions/setup-go@v4
         with:
           go-version: '^1.16'
       - name: Checkout repository
@@ -27,7 +27,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        go: [1.18, 1.19, '1.20']
+        go: [1.18, 1.19, '1.20', 1.21]
         include:
           - os: ubuntu-latest
             go-build: ~/.cache/go-build
@@ -40,7 +40,7 @@ jobs:
       GOPROXY: https://proxy.golang.org
     steps:
       - name: Set up Go ${{ matrix.go }}
-        uses: actions/setup-go@v3
+        uses: actions/setup-go@v4
         with:
           go-version: ${{ matrix.go }}