Update version of actions/checkout action used in Compile Examples CI workflow

The action now has a default fetch-depth value of 1, so there is no need to specify this input.

Author: per1234

.github/workflows/compile-examples.yml

@@ -13,9 +13,7 @@ jobs:
        ]
 
    steps:
-     - uses: actions/checkout@v1
-       with:
-         fetch-depth: 1
+     - uses: actions/checkout@v2
      - uses: arduino/actions/libraries/compile-examples@master
        with:
         github-token: ${{ secrets.GITHUB_TOKEN }}