Upgrade to the latest version of the setup-go github action

The beta version utilizes the deprecated `set-env` and `add-path` commands. More details at https://github.blog/changelog/2020-10-01-github-actions-deprecating-set-env-and-add-path-commands/

Author: AntonNguyen

.github/workflows/ci.yml

@@ -45,7 +45,7 @@ jobs:
 
     steps:
       - name: Set up Go
-        uses: actions/setup-go@v2-beta
+        uses: actions/setup-go@v2.1.3
         with:
           stable: 'false'
           go-version: ${{ matrix.go }}