ci: use go 1.21

.github/workflows/ci.yml

@@ -13,13 +13,13 @@ jobs:
 
       - uses: actions/setup-go@v4
         with:
-          go-version: '^1.20'
+          go-version: "^1.21"
 
       - name: Build
         run: go build .
         env:
           CGO_ENABLED: 0
-  
+
       - uses: actions/upload-artifact@v3
         if: ${{ github.event_name == 'push' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch) }}
         with: