docs: update dependencies and improve CI robustness

- Update Go version in README from `1.20.x` to `1.21`

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

README.md

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go-version: [1.20.x]
+        go-version: [1.21]
     steps:
       - name: checkout source code
         uses: actions/checkout@v3