Improve CI workflow

Author: andyone

.github/workflows/ci.yml

@@ -37,7 +37,7 @@ jobs:
 
     strategy:
       matrix:
-        go: [ '1.18.x', '1.19.x', '1.20.x' ]
+        go: [ '1.18.x', '1.19.x', '1.20.x', '1.21.x' ]
 
     steps:
       - name: Checkout
@@ -72,7 +72,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v4
         with:
-          go-version: '1.19.x'
+          go-version: '1.20.x'
 
       - name: Download dependencies
         run: make deps