chore: check-prelude also for Std

.github/workflows/check-prelude.yml

@@ -11,16 +11,18 @@ jobs:
         with:
           # the default is to use a virtual merge commit between the PR and master: just use the PR
           ref: ${{ github.event.pull_request.head.sha }}
-          sparse-checkout: src/Lean
+          sparse-checkout: |
+            src/Lean
+            src/Std
       - name: Check Prelude
         run: |
           failed_files=""
           while IFS= read -r -d '' file; do
             if ! grep -q "^prelude$" "$file"; then
               failed_files="$failed_files$file\n"
             fi
-          done < <(find src/Lean -name '*.lean' -print0)
+          done < <(find src/Lean src/Std -name '*.lean' -print0)
           if [ -n "$failed_files" ]; then
             echo -e "The following files should use 'prelude':\n$failed_files"
             exit 1
-          fi
+          fi