Update actions/checkout action to v3

.github/workflows/code-coverage.yml

@@ -11,7 +11,7 @@ jobs:
     name: Update coverage badge
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           persist-credentials: false # otherwise, the token used is the GITHUB_TOKEN, instead of your personal access token.
           fetch-depth: 0 # otherwise, there would be errors pushing refs to the destination repository.