Update actions/checkout action to v2 (#240)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

.github/workflows/ci.yml

@@ -38,7 +38,7 @@ jobs:
         with:
           go-version: 1.16
       - name: Checkout code
-        uses: actions/checkout@v1
+        uses: actions/checkout@v2
       - name: Install
         run: |
           git config --global user.email "github@spam.cozycloud.cc"