Cleanup CI configuration

Author: bastelfreak

.github/workflows/checks.yaml

@@ -23,8 +23,6 @@ jobs:
     steps:
       - name: Checkout current PR
         uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
 
       - name: Install ruby version ${{ matrix.cfg.ruby }}
         uses: ruby/setup-ruby@v1