chore: update Go version and golangci-lint, add support for Go 1.21

- Update the Go version from `1.16` to `1.18`
- Update the golangci-lint version to the latest
- Update the supported Go versions to include `1.21`

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

.github/workflows/go.yml

@@ -15,19 +15,19 @@ jobs:
       - name: Setup go
         uses: actions/setup-go@v3
         with:
-          go-version: '^1.16'
+          go-version: '^1.18'
       - name: Checkout repository
         uses: actions/checkout@v3
       - name: Setup golangci-lint
         uses: golangci/golangci-lint-action@v3
         with:
-          version: v1.49.0
+          version: latest
           args: --verbose
   test:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        go: [1.14, 1.15, 1.16, 1.17, 1.18, 1.19, '1.20']
+        go: [1.18, 1.19, '1.20', 1.21]
         include:
           - os: ubuntu-latest
             go-build: ~/.cache/go-build