🍏🚑 Fix checkout action failing

Ref. actions/checkout#766

Author: bramus

.github/workflows/CI.yml

@@ -16,7 +16,7 @@ jobs:
         dependencies: ['', '--prefer-lowest --prefer-stable']
     steps:
       - name: Checkout
-        uses: actions/checkout@v2.3.4
+        uses: actions/checkout@v2
       - uses: shivammathur/[email protected]
         with:
           php-version: ${{ matrix.php }}