Fix checkout

Author: mdboom

.github/workflows/ci.yml

@@ -432,7 +432,6 @@ jobs:
       - name: Checkout universally-skipped test reporter
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
         with:
-          ref: main
           fetch-depth: 1
           sparse-checkout: |
             ci/tools