Bump actions/checkout from v1 to v2.3.4

Bumps [actions/checkout](https://github.com/actions/checkout) from v1 to v2.3.4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v1...5a4ac90)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -36,7 +36,7 @@ jobs:
     name: PHP ${{ matrix.php }} - Laravel ${{ matrix.laravel }} --${{ matrix.prefer }}
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
 
     - name: Setup PHP
       uses: shivammathur/setup-php@v2